A COUNTRY-BASED REVIEW IN COVID-19 RELATED RESEARCH DEVELOPMENTS

. The COVID-19 pandemic has turned our life topsy-turvy. It has bought a massive change in all sectors around the world. A great number of research papers have already been published accounting for various aspects of the COVID-19 issue, owing to the ever-increasing interest in this hot area. The essential data is gathered using the well-known and dependable search engine SCOPUS. We looked at research papers, journals, and reviews from 25 leading countries to highlight a comprehensive study of research output through COVID-19 papers. This study focuses on the top authors, leading articles, and journals from various nations, the percentage of published papers in various fields, and the top collaborative research work from different authors and countries. USA, UK, China, Italy, and India have all made a significant contribution to COVID-19 research. The USA is the leading country followed by UK and China but for H-index China is in the best position. The highest number of papers has been developed in the area of “medicine”. The Harvard Medical School of the UK contributed the highest number of papers followed by the University of Toronto of Canada. Professor K. Dhama of India has published the highest number of papers while C. Huang of China received the highest number of citations. It also highlights that several authors have differing opinions on the efficacy of taking the medicine remdesivir. Our research provides a complete and comprehensive image of the virus’s current research status, or in other words, a roadmap of the present research status.


Introduction
The world is in disarray today as a result of the coronavirus's sudden attack.In December 2019, an epidemic of this lethal virus was reported in China's Wuhan city of Hubei Province.The virus spread fast over the world as a result of developed international communication.At the time of the virus's initial outbreak, countries like the United States of America (USA), Italy, France, Brazil, and the United Kingdom (UK) are in upheaval.Since its beginning in 2019, WHO recognized the fatal virus as COVID-19.This virus is most commonly referred to as coronavirus because of its crown-like structure.The virus poses a global health emergency throughout the world.To begin, practically most of the countries on Earth are being forced to go into lockdown day after someday to fight this lethal virus, as physicians or scientists are at a loss for how to combat it.Individuals are directed/asked to remain in their homes.The first wave of coronavirus killed a large number of people, including doctors, police officers, health care personnel, and teachers, as well as many ordinary citizens.This funeral procession was watched by the entire world.The coronavirus has a profound effect on social life and the environment.The world economy suffered tremendous damage as a result of the prolonged shutdown.Numerous businesses have ceased operations.The mode of transportation must be halted.As a result, a large number of people lose their work and become jobless.Many are compelled to switch jobs in order to survive.Work from home is a trend that began in the industry, information technology, education, and other sectors.So, researches have been started towards various sides like socio-economic, environment along with the discovery of medicine.
There are several bibliometric studies on COVID-19 publications.To the best of our knowledge, our study is the first one focusing on the contemporary COVID-19 literature depicting a comprehensive global research scenario.We have developed a country-wise review analysis of the current research status that emerged due to the sudden appearance of COVID-19.Su et al. [49] presented a detailed and comprehensive bibliometric study providing research output of various institutions, countries, scientists or physicians, etc.The objective of their study is to analyze the most cited papers as well as to find the research trend, and provide necessary information to the people.They reviewed 51 047 papers, and in this matter, they rely on the Web of Science.According to their observation, The British Medical Journal is in the leading position in terms of publication but in terms of citations, The Lancet and New England Journal of Medicine is in the focus, and are in a better position.By the bibliometric study, Kappi et al. [30] would like to seek the research priorities highlighting top-cited publications, top-ranking institutes, top-contributing countries, top-publishing, top-citing, and top H-indexing journals, topsub disciplines, top-language of research, etc., and so many aspects.They considered a total of 17 333 different types of published articles from the web of science.According to their study, The British Medical Journal ranks first contributing 663 papers (3.87% of the total publication) followed by the Journal of Medical Virology with 325 publications.The famous journal New England Journal of Medicine received the highest number of citations amounting to 5881 followed by The Lancet with 4780 citations, and the Journal of American Medical Association (JAMA) has a total of 4634 citations.But in the light of the H-index JAMA occupies the second position with a 29 H-index and the journals New England Journal of Medicine and The Lancet have an H-index of 32 and 26 respectively.Keyword "COVID-19" is mostly used with a total of 6180 in number followed by SARS-Cov-2 having 1926 times.The keyword "coronavirus" appears 1570 times.The bibliometric study of Vasantha Raju et al. [52] reflects that India is also playing an impressive role to enhance the progress of research on COVID-19.The authors framed their study based on the published papers on SARS-COV-2 using the WHO database as the data source.They observed that most of the researchers belong to either AIIMS or ICMR institutes.Indian Journal of Medical Research (IJMR) published a total of 14 papers within the time under consideration which remdesivir reduces the time it takes for patients who are discharged without oxygen.They emphasized the use of masks, maintaining social distancing, and tracing contacts.Ghadir et al. [15] identified seventy different risks in a supply chain under seven categories due to the outbreak of COVID-19.Mondal and Roy [38] developed supply chain models to retain supply among production centers and hospitals during the COVID-19 pandemic situation.Tirkolaee et al. [51] presented a multi-period multi-echelon multi-product supply chain network of face masks during the COVID-19-pandemic.They used Multi-Objective Grey Wolf Optimization Algorithm, and Non-Dominated Sorting Genetic Algorithm II to solve the proposed model, and to find Pareto optimal solutions.Khalilpourazari et al. [31] used a Gradient-based Grey Wolf Optimizer for modeling and prediction of the COVID-19 pandemic.Aydin and Tirkolaee [3] analyzed country-level growth dynamics of COVID-19.Babaee Tirkolaee et al. [4] presented a sustainable medical waste management policy under the COVID-19 pandemic situation.
In this paper, we present a bibliometric study on different aspects of COVID-19 which can highlight a complete picture of research status or progress on COVID-19.Health emergencies are going on all over the world due to the sudden occurrence of coronavirus, so there is a consensus on the progress of research on drugs or vaccines.By this study, it is possible to know which country is at which stage of research.Such type of study also analyses the effect on the social, economic, psychological, environmental, information technology, and industrial sectors.Though the medicinal field is in the leading position in terms of publication of covid related papers, other fields are also not far behind in this regard.
Scopus database is used for the collection of papers/articles as Scopus is a very well-known reliable source and contains a large dataset.The purpose of the present study is to explore the current research status of the deadly virus COVID- 19.By this study, we have tried to comprehend which key realizations have been achieved to fight against the fatal virus.By this paper, we intend to highlight: (i) Which countries are the leader in COVID-19 research?(ii) Which author has published the highest number of papers?(iii) Which authors have received a very good number of citations?(iv) How far research has been advanced in discovering fruitful medicine or vaccine around the world?(v) Which institute has put special emphasis on research of COVID-19?(vi) Which measures might be taken by the common people to save themselves from infection of the fatal virus?Here we have considered the papers based on the number of citations.Naturally, papers published in early 2020 have received more citations than the recently published papers.During that period there are no available medicines or vaccines in the world.Thus, the consciousness and carefulness of the people were very important at that stage.(vii) How much this calamitous situation has globally impacted other sectors like socio-economic, education, business, environment, etc. (viii) Is there any sector which is not covered by the research that means is there any gap in research?(ix) Is there any mediator for escalating/accelerating the infection?(x) Since most of the papers considered here included clinical trials, real case studies of confirmed infected patients of different hospitals separately considering male and female, the study can delineate which sex are mostly infected by the COVID-19 or what steps may be adapted after recovery from the disease?.
The rest of the paper is arranged as follows: Section 2 discusses the methodology.Section 3 discusses Mathematical expressions and corresponding graphical representation of COVID-19 infections in the top six countries.The result as well as the necessary discussion is provided in Section 4. Major findings are presented in Section 5. Finally, a comprehensive conclusion is presented in Section 6.

Methods
The well-known database SCOPUS is used to collect data for this study.It is a universally accepted and consistent database for scientific publications.SCOPUS covers 22 794 active titles and 13 583 inactive titles in its database.When searching for documents that had used "COVID-19" in the title or abstract or keywords, SCOPUS' search engine revealed a total of 207 854 documents up to 14th October 2021.We limit the search result to English language and Journal publications.Next, we limit the search result to document types "article", and "review".In this way, we arrived at a total of 143 686 documents (122 465 articles, and 21 221 reviews) for this study.Details of the article selection procedure are given in the Figure 1.A document will be considered for a country if one or more authors used affiliation of that country.Suppose a document has N authors from M different countries then it will be considered in the account of all M countries associated with its authors.Thus, a document may be possible to display in the account of more than one country.Based on the final data set of 143 686 documents we find the leading twenty-five productive countries in COVID-19 research.
Country-wise collected data are arranged and classified based on different indicators like the total number of publications (TP), H-index, and citation thresholds for 50, 100, 200, 500, and 1000 citations.A country has X number of publications and we have arranged contributing authors, institutions, and keywords based on those X publications.Thus, it may be possible that an author/institution can lead in a profile for a different country if it has strong collaboration with authors/institutions of that country.In this study, we also highlight frequently used keywords for the leading countries to explore research directions on COVID-19-related issues.

Mathematical expressions and corresponding graphical representation of COVID-19 infections in the top six countries
More than 230 countries in the world have more or less been affected by the calamitous virus.According to the world o meter as of 30th June, 2021 more than 182 million people are infected and the death toll is more  than 3.9 million.The countries USA, India, Brazil, France, Russia, and Turkey secure the first six ranks from the top.The countries the USA, Brazil France had been attacked all of a sudden in the midway of February 2020.

Graphical representation of number of infections of top six countries
We have fitted the infected curve with three trend lines (straight lines) in the case of the USA (see Fig. 2).The equations of the trend lines are  = 25698 − 2000000;  = (1000000) − 40000000; and  = 33008 + 10000000.
It is observed that between 40 and 58 weeks (04/11/2020 and 05/03/2021) the gradient of the straight lines is nearly four times the same between 9 and 40 weeks (11/04/2020 and 28/10/2020) in the case of the USA.In India, five straight lines (see Fig. 3) are needed to capture the graph of the number of infections.The equations of the trend lines are shown in Figure 2. We observe that in India, between 62 and 70 weeks (02/04/2021 and 26/05/2021) the trend line is steeper than the others.That means the number of infections rapidly increases in

Research outcomes
In Table 1 we consider top 25 productive countries based on TP in COVID-19 related research.Ranking is given based on the TP.
Table 1 includes 25 countries in terms of the TP on the current burning topic COVID-19.The Table 1 will help to overview the research scenario at a glance.Among twenty-five countries, eleven belong to Europe (UK, Italy, Spain, Germany, France, Turkey, Netherlands, Switzerland, Poland, Belgium, and Sweden); two in North America (the USA, and Canada); Brazil in South America; eight in Asia (China, India, Pakistan, Iran, Saudi Arabia, Japan, Indonesia, and South Korea); Australia in Oceania, and two are in Africa (South Africa, and Egypt).The USA comfortably is in the leading position having published 38 939 research papers/articles within    Iran, Pakistan, and, Egypt has no papers over the threshold of 1000 citations but these countries respectively have five, two, and three papers over the threshold of 500 citations.According to the 200, 100, and 50 citation thresholds, the USA is in the leading position within the Table 1.Though Indonesia is at the twenty-second position in the Table 1 of the top 25 countries in respect of TP, it has the least H-index (40).All other countries in Table 1 except Indonesia have an H-index value of more than fifty.Figure 8 presents the top ten countries according to the H-index.
Figure 9 presents the top ten countries according to number of papers more than the threshold of 100 citations.Almost all countries around the world are strongly involved in COVID-19 related research.In order to identify the leading ones, let us look into the results according to some well-known bibliometric indicators.Table 1 presents the 25 most productive countries in this field.In Table 2 we prepared a ranking of the top 20 countries by their research performance.Research Score (  ) is calculated based on the indicators TP, H-index,    • Now look at the spearman's rho correlation coefficient to examine correlation among the different rankings based on publications, H-index, T50 index, and our combined index.We considered ranking of top 10 countries of Table 2 under different the bibliometric measures to determine the spearman's rho correlation coefficient and results are presented in Table 3.
From Table 3, one may note that our combined index is positively correlated with all the three indexes TP, H index, and T50.Ranking of the universities under the total publication and H-index are negatively correlated while total citation and H-index are almost perfectly correlated.Upcoming Sections 4.1-4.11discuss the contribution of each of the leading countries separately in terms of leading topics, subject areas, authors, and institutions.Moreover, it explores leading articles of these countries and reviews the impact of those articles.COVID-19 research.It is also seen that most of the published papers belong to the field/area of medicine which is very obvious because researchers are actively engaged in the discovery of effective medicine or vaccine to save from the grip of the fatal virus.The USA is the worst affected country in the world and so the USA reinforced to prepare the vaccine or medicine for immediate remedy.Thus, the subject area of medicine has gained utmost priority and immediate urgency.Subject areas "Social Sciences" and "Biochemistry, Genetics and Molecular Biology" are respectively the second, and the third leading research areas in the USA for COVID-19 research.Harvard Medical School has the highest number of publications with a total of 2140 publications followed by Massachusetts General Hospital, which has 1061 publications in COVID-19 research.Table 5 presents information for the top ten most-cited COVID-19-related articles written by authors from the USA.Richardson et al. [44] examined the characteristics, comorbidities, and outcomes of the 5700 patients admitted to hospitals in New York City with the symptom of COVID-19.The number of citations (3476) ensures the quality of the paper.Holshue et al. [24] discussed the first case of coronavirus in the USA.The paper has been published in the well-reputed New England Journal of Medicine.A clinical trial of different drugs started in war-time activities.A trial of lopinavir-ritonavir in adults hospitalized with severe COVID-19 has been noted by Cao et al. [8].It is supposed that the drugs lopinavir, and ritonavir may be effective to fight against the deadly virus.This paper is also included in the list of leading articles in the UK and, China.The paper has also a good number of citations.The effect of the fatal coronavirus was so horrible that the whole world was keenly waiting for the preventive vaccine.So, the paper reinforcing the clinical trials of lopinavir-ritonavir has received major attention from researchers.Beigel et al. [6] also submitted a report about the use of the much-discussed drug remdesivir.Mao et al. [37] pointed out the neurologic manifestations.They think that different aspects of neurologic manifestations are yet to be explored.They studied patients admitted for one month (16/01/2020 to 19/02/2020) to the Huazhong University of Science and Technology in Wuhan of China to reach their conclusion.Mao et al. [37] also belongs to the list of authors in China.Ackermann et al. [1] compared two types of lungs of seven expired patients -one from COVID-19 virus and the other from acute respiratory distress syndrome and observed that there exist severe endothelial injury and angiocentric inflammation in the lungs of dead patients from the COVID-19 virus.Wan et al. [53] studied the structure of coronavirus (2019n-CoV) that emerged from the Wuhan province of China based on the prior knowledge of SARS-CoV-2.They concluded that 2019n-CoV-2 uses Angiotensin-Converting Enzyme-2 (ACE2) as its host receptor and may be severe to humans due to its mutant nature.Rothan and Byrareddy [46] focused on the symptoms of patients, way of transmission, and pathogens and emphasizes finding out the way to prevention of the virus.Out of the ten leading papers five (05) have been published in the famous journal New England Journal of Medicine.So, we can state that researchers frequently choose this journal for the publication of their papers.

United Kingdom
Section 4.2 presents contribution of United Kingdom (UK) in COVID-19 related research.Table 6 presents the top fifteen authors, subject area, and institution of the UK in terms of TP.
Professor L. Smith has 57 publications securing the top position in The virological assessment of hospitalized patients with COVID-2019 was reviewed by Wolfe et al. [56] of the UK.The study was published in Nature and received 2685 citations in a short time.It shows that the study has received a lot of attention from the researchers.The effect of remdesivir was reported by Beigel et al. [6].To examine the effect, they purposely applied a 10 days course of remdesivir and placebo to the 1062 patients and observed the result.They saw that patients treated with remdesivir quickly recovered than the patients treated without remdesivir.It also reduces tracheal infection of the COVID-19 confirmed patients.Holmes et al. [23] have shown their interest to evaluate the diverse effects of the pandemic on society including social and mental health.They stress the collaborative and inter-disciplinary research and collection of data across the globe to find the fruitful result of the research.Nicola et al. [39] also presented a review paper depicting the global socio-economic scenario due to the sudden advent of the calamitous virus.They tried to explore the changes pre-and post-pandemic situations in different sectors like education, production of commodities, the field of medicine, the food sector, etc. Sohrabi et al. [48] made a review of the 2019 novel coronavirus and inferred that rigorous surveillance, minute observation, and hard work are urgently needed to comprehend the nature of the devastating virus.Tay et al. [50] analysed the different mechanisms of SARS-CoV2, and emphasize immunopathogenesis.They inferred that T-cell may take an effective role to prevent the infection of the virus.They also emphasized more research in this direction.Wang et al. [54] studied the viral infected adult patients admitted to the ten hospitals in the Hubei province of China.The patients were treated with a controlled dose of remdesivir drug but after due observation, no significant result has been obtained of the many discussed remdesivir drug.Huang et al. [27] made a case study taking into account forty (41) patients admitted in a hospital in Wuhan city of China being infected by a 2019 novel coronavirus.The median age of the patients was 49 and they observed that pneumonia was common of all patients with different levels of chest injury and some of them have to be treated in ICU.But surprisingly it is seen that ICU patients are in a better position than non-ICU patients in terms of plasma level.The paper was published in the world-famous medical journal "The Lancet" bearing a magnificent number of citations with 18 794 ensuring its quality.To characterize the deadly virus, Guan et al. [19] gathered data of 1099 patients from 552 hospitals with different demography of China.The paper got a remarkable number of citations with a total of 12 264 within a very short time.After the investigations of 191 patients admitted to two hospitals in China (Jinyintan Hospital, and Wuhan Pulmonary Hospital), Zhou et al. [62] summarised that patient with more than 1 g/ml d-dimer have a very high risk.The paper was published in the highly reputed medical journal "The Lancet" and received over 10 000 citations.Zhu et al. [64] has given importance to the mode of transmission, an interval of reproduction, clinical spectrum, and above all stress on the determination of strategy how to check the spread of the virus.They also pointed out the continuous and minute observation of the characters of the virus.Investigation about the clinical and epidemiological characteristics of 99 patients from Wuhan Jinyintan Hospital has been done by Chen et al. [10], and they come to the conclusion that the virus has become very severe to the aged males having comorbidities.They also suggest more and deep investigation/study for the prediction of the risk of mortality.Zhou et al. [63] provided a detailed study of the 2019 novel SARS CoV-2 pointing out the possible responsible agent for current catastrophe in human life.They also notice the existence of nucleotide positive and viral-protein seroconversion of all patients with confirmed cases.They focus on more exploration in this regard.Lu et al. [36] interpreted that the 2019 novel coronavirus has a strong affinity with the human receptor ACE-2.They also guessed that while bats may have been the original host, some animals may have acted as a catalyst to spread the virus to humans.After a careful examination of a household with six patients, Chan et al. [9] stressed the need of avoiding human-to-human transmission of the virus.Xu et al. [59] hope that their research will help to explore pathogens, and will be able to assist in mitigating the mortality rate.initial pieces of evidence about the impact of the 2019 novel coronavirus received from China.Researchers all over the world followed research outcomes and patient observation from various Chinese hospitals.

Italy
Section 4.4 presents contribution of another badly COVID-19 affected country, Italy in COVID-19 related research.Table 10 presents the top fifteen authors, subject area, and institution of Italy based on the TP.
Professor Giuseppe Lippi from the University of Verona has the most (87) number of publications.Note that, Professor Lippi also leads in the USA.This is an incredible performance as he leads in two countries (USA and Italy) through collaborative works.Professor G. Landoni and F. Ciceri are in the second and third positions with 61 and 55 publications respectively.The top fifteen authors of Italy have more than or equal to forty publications.Among the 11 476 publications, 7951 are in the area of medicine."Biochemistry, Genetics and Molecular Biology" and "Immunology and Microbiology" are the other two leading research areas in Italy.There are more than eight hundred publications in the areas "Social Sciences" and "Environmental Science".Interestingly, there are 533 publications on Psychology.This evidence shows that fear of COVID-19 and its obligations has a huge impact on public psychological health.Università degli Studi di Milano and Sapienza Università di Roma are two the leading institutions with 1140 and 1129 publications on COVID-19 related research.Five universities of Italy have more than five hundred publications.

India
Table 11 presents the top fifteen authors, subject area, and institution of Italy based on the TP.Professor K. Dhama, principal scientist of the Indian Veterinary Research Institute, Izatnagar has authored a total of 107 papers.He is the most productive author for India as well as the World in COVID-19 related research.Professor R. Tiwari is in the second position on the list of leading Indian authors with 56 publications.Among the 10 726 articles of India 5314 articles are published in medicine-based journals and 1749 in the area "Biochemistry, Genetics and Molecular Biology".More than twelve per cent of articles were published in "Social Sciences" journals.Indian researchers also focused on "Pharmacology, Toxicology and Pharmaceutics" journals and published 1156 articles in this area.All India Institute of Medical Sciences, New Delhi is the leading institution in India with 526 publications.Five institutions of India in Table 11 have more than 200 publications.

Canada
Table 12 presents the top fifteen authors, subject area, and institution of Canada based on the TP.Nicola Luigi Bragazzi from York University, Toronto is the leading author in the list of productive authors from Canada (see Tab. 12).S. Murthy has 35 publications on COVID-19 and gets the second position in Canada.The top eleven authors in Table 12 have more than or equal to twenty publications.Among the 6516 articles of Canada, 4049 articles are published in medicine-based journals and 1010 in the area of "Social Sciences" journals.More than ten percent of articles were published in "Biochemistry, Genetics and Molecular Biology" journals.The University of Toronto leads comprehensively with 1527 publications followed by The University of British Columbia in the list of productive institutions from Canada.Seven institutions of Canada in Table 12 have more than 400 publications.

Spain
Table 13 presents the top fifteen authors, subject area, and institution of Spain based on the TP.L. Smith is the leading author in the list of productive authors from Spain (see Tab. 13) followed by A. Torres.The top five authors in Table 13 have more than or equal to twenty-five publications.The top three leading areas of Spanish authors in COVID-19 research are "Medicine", "Social Sciences", and "Environmental Science".It is noticeable that more than twelve percent of articles of Spanish authors in COVID-19 research are published in "Environmental Science" related journals.The University of Barcelona leads among the Spanish institutions with 528 publications followed by Hospital Clinic Barcelona, which has 518 publications in COVID-19 research.Seven institutions of Spain in Table 13 have more than 300 publications (Tab.14).
Discussion on the leading articles of Italy, India, Canada, Spain

Italy
The cohort study of Grasselli et al. [17] over 3988 critical patients in the Lombardy region of Italy reveals the higher mortality rate of the patients.These patients have an urgent need of ICU, and Invasive Mechanical Ventilation (IMV).Remuzzi and Remuzzi [43] attempted to depict a picture of healthcare scenarios of Italy after the outbreak of the pandemic.They also reiterated that if the trends of the graph persist, the Italian Government has to take immediate action to increase the health infrastructure to get rescue from such a terrible pandemic situation.Grein et al. [18] used the remdesivir drug among the 61 hospitalized confirmed infected patients with an oxygen level of less than or equal to 94 oxygen levels and found that this drug may be beneficial to the critically ill.Chinazzi et al. [11] use a global meta-population disease transmission model.They concluded that inter-national travel restrictions could slow the spread of the novel coronavirus.They also found that early detection, hand washing, self-isolation, and household quarantine are more helpful than travel limitations in preventing the spread of the deadly virus.Lechien et al. [34] investigated the situation of hospitalized patients with confirmed infection to see the existence of olfactory and gustatory disorder among the patients and observed that these symptoms are frequent/prevalent among European patients.They also stressed the need of identifying the symptom anosmia or ageusia which is regarded as a crucial symptom of COVID-infected patients.Bikdeli et al. [7] looked at the pathogenesis, epidemiology, and outcomes of the patients and highlighted the need for precaution having a thrombotic disease.

India
Singhal [47] presented a comprehensive review of COVID-19.In this review paper, the author sheds light on the different features like symptoms of the infected people, and process of treatment, etc. Rajkumar [42] discussed that COVID-19 has a major adverse effect on the mental health of the common people like anxiety, depression, and mental stress.They also summarized that more research may unfold different aspects in this regard especially for the people belonging at a higher risk due to poor health.After going through the 27 articles Rodriguez-Morales et al. [45] presented a systematic review and meta-analysis in Indian perspective with three basic objectives -to summarize the results obtained from various laboratory-based clinical examinations, and observations, to review the infrastructure for critical patients, and to estimate the prevalence/frequency of co-morbid patients.

Canada
After going through some research papers related to social and behavioural science Baval et al. [5] talked about the prevention of threat, social, and behavioural changes, improvement of science communication, leadership, stress, etc. during the pandemic.They also pointed out the research insights of the earlier published papers as well as the gaps.They hope that the paper may help/assist the policymaker to reduce the potentially fatal impacts of COVID-19 by taking immediate intervention in this regard.Chu et al. [12] presented a systematic review and meta-analysis by collecting a dataset from 21 standard sources recognized by the World Health Organisation (WHO) across 16 countries of six continents.They used the data after careful and proper screening on both health care workers and common people.They observe that close contact with human beings may accelerate the spread of the virus.After a detailed study, they suggest the three main ways for prevention from the spread of SARS-CoV-2 -firstly on keeping greater than a 1 m distance between each other, second the optimal use of masks namely N-95, surgical and 12-16-layer cotton masks, and the third is the use of goggles, face shields, etc. for protection of eyes.They added that N-95 masks are more effective than surgical masks for health care workers, and the common people may use N-95 masks as well as surgical or cotton masks.Jin et al. [28] prepared a guideline for the diagnosis and treatment of COVID-19 infected patients based on the available primary data of Zhongan Hospital of Wuhan University.Since the fatal virus is transmitted through droplets, they strongly recommended avoiding unnecessary travel and advised to stay at home.They recommended some measures for frontline line workers like the doctors, nurses, scientists, police, and other people associated with the hospitals, etc.They have suggested various measures for the treatment of the infected people like continuous monitoring with different blood tests, and other clinical examinations.They also suggested oxygen therapy and ECMO support for critical patients.They also pointed out a very controversial matter of whether the drug lopinavir, and ritonavir are beneficial or not for corona-infected patients.After deep observation, they summarised that these drugs may be beneficial for the patients if applied at an early stage, but give no fruitful result for late application.They also added that further exploration is needed in this regard.Emanuel et al. [13] proposed six recommendations for equal distribution, and optimal use of scarce medical resources, as well as a roadmap for equal access to facilities, and opportunity for all.Through their recommendations, they brought attention to a few key points.According to their opinion, equal emphasis should be equally given to all types of patients (both-COVID, and non-COVID), strong efforts should be made to save the most lives and maximum benefits of individuals, testing, use of PPE should be enhanced, ICU for critical patients should be provided, and special attention is to be given on the researchers as they can do their work freely, and fearlessly for the greater benefit of the society in future.They also stated that patients should be given priority based on scientific evidence rather than on a first-come-first-served basis.

Spain
List of leading articles of Spain are already discussed earlier as these are concurrently listed in another countries namely UK, Italy, and Canada.

Germany
Table 15 presents the top fifteen authors, subject area, and institution of Germany based on the TP.German virologist Christian Drosten leads the list of productive authors in Table 15 with 58 publications in COVID-19 research closely followed by another virologist Victor M. Corman from Charité -Universitätsmedizin Berlin, who has 54 publications.The top five authors from Germany in Table 15 have more than thirty publications.The top three leading areas of German authors in COVID-19 research are "Medicine", "Biochemistry, Genetics and Molecular Biology", and "Social Sciences".Charité -Universitätsmedizin Berlin leads comprehensively among the German institutions with 525 publications followed by Ludwig-Maximilians-Universität München.The top five institutions of Germany in Table 15 have more than or equal to 250 publications.
The 2019-nCoV has posed a serious global problem.People across the world are directionless to find a way to save themselves from the grasp of the deadly virus.Researchers of almost all the countries are engaged to find the way of prevention of infection, and method of treatment, etc. German researchers have also come forward to carry on the research in this regard Table 16 presents list of leading articles of Germany.Hoffmann et al. [22] deeply investigated the existence of any cell or any kind of host in the human body that has an affinity to attract the SARS CoV-2 or if there exist any matters that prevent the access of virus in the human body.They observed that ACE2 accelerates the easy entrance of the virus into the human body.They also demanded that the entry of lethal virus may be blocked by an inhibitor of the cellular series protease TMPRSS2 which is employed by SAERS-CoV-2 for S protein priming.Kampf et al. [29] inquired whether inanimate things like metal, glass, or plastic are regarded as a carrier of coronavirus or not.They inferred that such inanimate things may persist the virus for up to 9 days.Chemical reagents like ethanol, sodium hypochlorite, and hydrogen peroxide can disinfect the virus within one minute up to a certain percentage.The positivity rate ( 0 ) is used to represent the speed/rate of virus's transmissibility.Positivity rate of the COVID-19 virus was estimated by Liu et al. [35].They show that if  0 is greater than one ( 0 > 1), infection is likely to increase, and if it is less than one ( 0 < 1), infection is going to diminish.According to their estimate, the mean  0 is 3.28 in mid-February, 2020 which is greater than WHO's estimate.Zhang et al [61] analyzed the x-ray crystal structure of SARs-CoV-2 in two different crystal forms, at 1.95 and 2.20 Å resolution, to identify the main protease and its complex (M pro or 3CL pro) which cuts the polyproteins translated from viral RNA to yield functional viral proteins.They also tried to provide a useful framework to find pyridine-containing inhibitors to discover anti-coronaviral drugs.

Australia
Table 17 presents the top fifteen authors, subject area, and institution of Australia based on the TP.Italian professor Giuseppe Lippi from the University of Verona and Australian Professor C Raina MacIntyre from Kirby Institute are leading jointly in the list of most productive authors in Australian publications related to COVID-19.The performance of Professor Giuseppe Lippi confirms well collaboration of Italy and Australia in COVID-19 related research.The top seven authors in Table 17 have more than or equal to twenty publications.Australian research papers are mostly published in medical journals.A notable 22% of research papers of Australia are published in social science-based journals.The University of Melbourne leads comprehensively among the Australian institutions with 856 publications followed by Monash University which has 729 publications in COVID-19.The top five institutions of Australia in Table 17 have more than 500 publications.Table 18 presents list of leading articles of Australia.

France
Professor Didier Raoult from Aix Marseille Université, France has 46 publications in COVID-19 related research, leads the list of most productive authors in France.Professor J.R. Lechien 19 have more than 500 publications.Table 20 presents list of leading articles of France.Gautret et al. [14] assayed whether hydroxychloroquine, and azithromycin are effective or not in lowering the viral load in covid infected patients.Based on a short sample, they observed that hydroxy chlorine helps lessen the viral load.They also inferred that using azithromycin in conjunction with hydroxychloroquine is more effective.Based on some clinical trials, Helms et al. [21] found that CT pulmonary angiography (CTPA) may strongly assist the severe covid patients with high pulmonary embolism (PE).They also showed that lung ultrasonography alone is unable to detect/uncover the proper cause of deterioration of covid patients.CTPA is extremely useful to explore the unknown and peculiar characteristics/symptoms in such cases.Gordon et al. [16] made a chemo-proteomic analysis to discover effective drugs for the treatment of covid patients.They also stressed the deciphering of the virus's mechanism responsible for it.They expect that their study will show a new avenue to fight against the different viruses along with the coronavirus.South Africa, Poland, Indonesia, Egypt, Belgium, and Sweden.We can see that the subject area "medicine" has the highest number of publications of all countries which is quite natural as the entire world is working hard to overcome the health crisis by seeking medicine or vaccine as early as feasible.In terms of paper publication, N.

Leading authors, subject areas, and institutions of remaining 15 countries
Ohmagari of Iran holds first place followed by J.R. Lechien of Belgium contributing 75 and 51 papers respectively.During this short time R. Pranata of Indonesia produced 49 papers securing the third position, and the remaining authors from those 15 countries contributed papers ranging from 16 to 40 in number.Universidade de São Paulo of Brazil put a good impression on carrying on the COVID-19 research.The institute submitted a total of 1074 papers.In terms of paper publication, the Tehran University of Medical Sciences is not also far behind.The institute developed 885 papers in this area.Among the 15 countries, these two institutes came in first and second place, respectively.

Keyword analysis of top five countries
According to the number of articles published, in Table 22 we have considered 25 keywords from the top five countries namely the USA, UK, China, Italy, and India, and sorted the keywords in descending order.The keyword COVID-19 appears to be near the top of the search results in each of the countries.It is quite natural because all the research papers are focussing here on different aspects of the COVID-19 virus.It is 26 343 in the USA.Then proceed to China, UK, Italy, and India in that order.Keywords like human, humans, coronavirus disease 2019, SARSCOV2, pandemic, and male and female have been used frequently.Since the clinical trials have been conducted on people of various ages, the keywords aged, and middle aged has been used frequently.In terms of the number of publications, the keyword virology has appeared 4187 times in the United States, however it is not on the list in the United Kingdom.The keyword COVID-19 ranks first in all five countries, with a significant difference in number between the United States and the remaining four.The differences  22 reveals that the keywords review and non-human are only found in India's list of keywords.Again, it is observed that in the Indian keyword list, the term epidemiology appears only 695 times and is placed last in the Table 22, whereas in the United States, the term virology appears at the final position and has a TP of 4187.Keyword, Major Clinical Study is not on the list for the United States or India, but it is on the list for the remaining three countries: the United Kingdom, China, and Italy.The Table 22 also shows that almost all of the keywords have significant numerical differences between the United States, and the remaining four other countries.They think that more exploration is required in this matter.Grein et al. [18] concluded that this drug may take an effective role for severe patients.After careful observations of hospitalized patients admitted to ten hospitals, Wang et al. [54] inferred that the remdesivir drug has no significant effect on the covid infected patients.Wiersinga et al. [55] observed that remdesivir is able in lowering the recovery time for non-severe patients.Beigel et al. [6] took into account of 1062 patients among which 541 are given remdesivir while the remaining 521 were applied placebo.It is observed that patients who received remdesivir recovered faster than those who are treated with a placebo.The drug is also helpful in reducing respiratory tract infections.(vi) Glimpse of mathematics in COVID-19 related research.

Discussion and analysis of important findings
Here we highlight some papers which contributes mathematical implications relevant to the topic.Aydin and Tirkolaee [3] discussed the country level calibration and prediction based on some well-known models like logistic model, exponential model, Gompertz model, SIR model and SEIR model using real data from different countries.They calculated goodness of fit and compared the efficacy of the above-mentioned models.
In the logistic model the total number of infected is calculated by the formula  where , , and  are the infection speed, inflection point (the point at which the maximum increase in the number of infected occurs), and the estimated number of infected once the pandemic ends respectively.Now,  ′′ () = (1− 2 )  2 (1+) 4 where () =  −(−)/ . ′′ () = 0 gives  = 1 which is possible only when  =  or  → ∞ and  is said to be point of inflection.When  → ∞,   =  giving horizontal asymptote and the flatten level of   .That means  ′  =  (1+) 2 = 0 ⇒  → ∞.In the exponential model, the total number of infected is calculated as  Next, they consider "Gompertz Growth Model".The number of infections is calculated by the formula,  where  and  are the transmission and the recovery rates respectively, and  is the incubation rate.
To examine the production, distribution, and recycling of face masks during the COVID-19 pandemic, a mathematical model of a sustainable Closed Loop Supply Chain Network (CLSCN) has been developed by Tirkolaee et al. [51].A multi-objective Mixed Integer Linear Programming (MILP) has been proposed to address the allocation, supply, production, distribution, collection, quarantine, recycling, reuse, and disposal within the proposed networks.They considered two types of supply chain networks-forward supply chain and reverse supply chain.Forward supply chain networks include different levels of suppliers, factories, distribution centers, customer centers, and reverse supply chain network includes recycling centers, collection centers, quarantine centers, and disposal centers.The basic objectives were to minimize human risks as much as possible using sustainable face masks along with the minimization of other cost which includes establishment cost, transportation cost and employment cost, and total environmental pollution within CLSCN keeping in the mind the social, economic and environmental impact.They proposed two multi-objective meta heuristic algorithm of Multi-Objective Grey Wolfe Optimization (MOGWO), and NAGA-II to overcome the complexity of the problem and validated the outcome of the proposed model by using real case study in Tehran of Iran.It is almost impossible to determine the future trends of the COVID-19 virus due to its presence of some stochastic parameters.Khalilpourazari et al [31] applied a new algorithm named Gradient -based Grey Wolfe Optimizer (GGWO) in the prediction of future trends of SARS-CoV-2 and demanded that the had proved its efficacy in the United States.They also hope that the proposed method will enable the researchers to solve the complex function in future.Like Particle Swarm optimization (PSO), the GGWO Starts with initial population and next find the dominant members of the wolves.In this way the wolves update their position in the solution space near the target.Mondal and Roy [38] presented a sustainable opened and closed supply chain (SOCLSC) planning to manage supply among production centers and various hospitals during the sudden outbreak of COVID-19 pandemic.A multi objective mixed integer programming (MOMIP) describing a two-stage SOCLSC in an uncertain environment is applied to solve the proposed model.The primary objective was to minimize the total cost (production cost, holding cost, and distribution cost), total time, and the weighted backlog amount as well as to maximize the social impact by increasing job opportunities in production system, proper handling of produced items, and optimal distribution of the available items.To deal with the uncertainty in different scenarios, they used Robust Optimization (RO) approach, and applied Augmented Weighted Tchebycheff Method (AWTM) to solve the model.

Conclusions
This bibliometric analysis of COVID-19 was designed with great care.Through this study, we try to depict a summary of global research progress on the current and burning issue.That is, we are aware of the research position to solve the present global health calamity.Here, we consider twenty five (25) leading countries across six continents that are actively involved in COVID-19 research.We have included different parameters to frame our study like TP, H-index, citation threshold, leading authors, subject area, institutions in terms of TP of those countries, and most commonly used keywords with TP of the top five countries to construct our analysis.
After careful study, we see that the USA is the leading country followed by UK and China but with respect to H-index China remains in a better position.The keyword COVID-19 is mostly used, and the highest numbers of papers have been developed in the area of medicine.The Harvard Medical School of the UK contributed the highest number of papers followed by the University of Toronto of Canada and Huazhong University of Science and Technology respectively.Professor K. Dhama India of the published highest number of papers while C. Huang of China received the highest number of citations followed by W. Guan of the same country.It is also seen that The Lancet, New England Journal of Medicine, Journal of American Medical Association (JAMA), The Lancet Psychiatry, and Nature are the pioneering journals attractive to the researchers for publication of their valuable work.All these journals are working hard to bring the essence of research to the world as soon as feasible.
We may suggest the following research fields that may be promising in near future.(i) Use of AI in research COVID-19 research.(ii) Use of data analysis to find several factors behind the infection.More exploration is required to find whether it is event-specific or not.(iii) Emphasis should be given to Interdisciplinary research, which may disclose/reveal a new perspective.(iv) Effects of prolonged lockdown on the environment, education,

Figure 2 .
Figure 2. Number of infections over time in USA.

Figure 3 .
Figure 3. Number of infections over time in India.

Figure 4 .
Figure 4. Number of infections over time in Brazil.

Figure 5 .
Figure 5. Number of infections over time in France.

Figure 6 .
Figure 6.Number of infections over time in Russia.

Figure 7 .
Figure 7. Number of infections over time in Turkey.

Figure 8 .
Figure 8. Top ten countries according to H-index.

Figure 9 .
Figure 9. Top ten countries according to number of papers more than 100 citations.

Section 4 .
3 presents contribution of China in COVID-19 related research.

(
i) USA, UK, China, Italy, and India have all made a significant contribution to COVID-19 research.Research on COVID-19 is being conducted in a variety of directions, which is a good sign of interdisciplinary research.In China it is observed infected patients have a history of going to or working local seafood markets in Wuhan city.It is observed three authors of China have published three papers that have more than 10 000 citations within a very short span of time.It has been observed by some authors that the quality of the environment has significantly improved due to the long duration of lockdown around the world which is a positive side of lockdown.(ii) We have made an important observation.The Lancet and New England Journal of Medicine, according to the Scopus database, are the pioneering journal in terms of citation ensuring their excellence.The Lancet remains in the highest position while New England Journal of Medicine secures the second position.

=
•  (−) where , ,  are the initial number of infected growth rate, and starting date of infection.But this model does not converge when it becomes larger.

=
•  −(−) where , ,  are the upper bounds of total number of infected, the growth rate, and the location parameter respectively.The maximum rate of increase in the number of infected occurs at  = ln   obtained from the differential equation  ′′ =  2  2  − ( − − 1  ) = 0 For calibration they used Python SciPy along with the Scikit Library.In the SIR model, the systems of quadratic equations ared  = −   (4)  d d (4)  = (  − ) (4)  d d  =  (4)  dwhere  and  are the transmission and recovery rates respectively, and lim →∞   , lim →∞   and lim →∞   exist.SEIR model is the extension of SIR model.In this model, the system of differential equations are given by d  = −

Table 2 .
Top 20 countries based their performance in COVID-19 related research.

Table 3 .
The spearman's rho correlation coefficient under different the bibliometric measures.

Table 4 .
Leading authors, institutions, subject areas, and keywords in COVID-19 research in USA.Section 4.1 presents contribution of USA in COVID-19 related research.Table4shed light on the top twentyfive authors, subject area, and institution of the USA in terms of TP.Professor Lippi, G possesses the highest position in the list of leading authors with 63 publications.Professor F. Krammer and Professor R.S. Baric respectively are the second and third-ranked authors for the USA in

Table 5 .
List of leading articles of USA.

Table 6 .
Leading authors, subject areas, and institutions in COVID-19 research in UK.

Table 7 .
Table 6 followed by Professor A. Zumla and Professor R.M. Eggo.The top five authors have more than fifty publications in COVID-19 related research.The world-famous institute the University of Oxford occupies first place with 1414 publications.The University List of leading articles in UK.It is earlier mentioned that the subject "medicine" is the highest priority, and focuses on this emergent situation.So, the medicinal sector has the most publication bearing the number 9237.Note that, leading subject areas in COVID-19 research are quite similar to the USA.Table7presents information for the top ten most-cited COVID-19 related articles written by authors from the UK.
Sohrabi et al. [48] International Journal of Surgery 1735 7 Multidisciplinary research priorities for the COVID-19 pandemic: a call for action for mental health science Holmes et al. [23] The Lancet Psychiatry 1617 8 The socio-economic implications of the coronavirus pandemic (COVID-19): A review Nicola et al. [39] International Journal of Surgery 1506 9 Remdesivir in adults with severe COVID-19: a randomized, doubleblind, placebo-controlled, multicenter trial Wang et al. [54] The Lancet 1455 10 The trinity of COVID-19: immunity, inflammation and intervention Tay et al. [50] Nature Reviews Immunology 1388 College London, and Imperial College London respectively have 1267 and 1149 publications in COVID-19 research and are in the second and third position in the list of the leading institution in the UK.An interesting observation is that the Table 6 contains mostly the university name which ensures the excellent performance of the universities in the UK in advancing the research on COVID-19.

Table 8 .
Leading authors, subject areas, and institutions in COVID-19 research in China.

Table 9 .
Table 8 presents the top fifteen authors, subject area, and institution of China in terms of TP.Professor H. Lu leads the list of leading authors in Table 8 followed by K.K.W.To and K.Y.Yuen.H. Lu has authored 57 research articles based on COVID-19 related issues.Expectedly, Chinese research works are evolved the majority in the area of medicine.Differing from the USA and UK, besides medicine, Chinese research works emphasized on research areas "Biochemistry, Genetics and Molecular Biology" and "Immunology and Microbiology".Huazhong University of Science and Technology, and Tongji Medical College are the leading List of leading articles of China.
institution in China for COVID-19 related research works.Seven institutions have more than five hundred publications.Table9presents the list of leading influential articles from China on COVID-19 related research works.

Table 10 .
Leading authors, subject areas, and institutions in COVID-19 research in Italy.

Table 11 .
Leading authors, subject areas, and institutions in COVID-19 research in India.

Table 12 .
After studying a patient admitted to the Central Hospital of Wuhan being infected by the virus who worked at the local seafood market in Wuhan city, Wu et al. [57] emphasized the importance of doing extensive research to explore the natural and intermediate Leading authors, subject areas, and institutions in COVID-19 research in Canada.
[37]s.Note that, the article developed by Cao et al.[8][Sl No. 13 in Tab.9] has been described in both the USA, and the UK, and the article presented by Mao et al.[37][Sl No. 14 in Tab.9] has been discussed earlier in the section of UK.The Table9reveals that the leading articles of China have received a significant number of citations; four out of ten papers have got more than 10 000 citations.Chinese articles get more citations as

Table 13 .
Leading authors, subject areas, and institutions in COVID-19 research in Spain.

Table 14 .
List of leading articles of Italy, India, Canada, Spain.

Table 15 .
Leading authors, subject areas, and institutions in COVID-19 research in Germany.

Table 16 .
is the second-ranked author in France with 40 publications in COVID-19 based research.The top eight authors in Table 19 have more List of leading articles of Germany.Genetics and Molecular Biology", and "Immunology and Microbiology".The National Institute of Health and Medical Research (Inserm) leads comprehensively among the Australian institutions with 1358 publications followed by AP-HP Assistance Publique -Hopitaux de Paris which has 886 publications in COVID-19.CNRS Centre National de la Recherche Scientifique also shows important presence among the institutions in France.The top five institutions of France in Table

Table 21
highlights the leading authors, subject areas, and institutions in COVID-19 research of the remaining 15 countries namely Brazil, Turkey, Iran, Saudi Arabia, Japan, Netherlands, Switzerland, South Korea, Pakistan,

Table 17 .
Leading authors, subject areas, and institutions in COVID-19 research in Australia.

Table 18 .
List of leading articles of Australia.The keyword retrospective study has been added to the Chinese keyword list once more, however, it is not included in the list of 25 keywords from the other four nations.The Table

Table 19 .
Leading authors, subject areas, and institutions in COVID-19 research in France.

Table 20 .
List of leading articles of France.

Table 21 .
Leading authors, subject areas, and institutions in COVID-19 research of remaining countries.