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Every year, around 12,000-61,000 people die of flu around the world (https://www.cdc.gov/). China was dealing with the outbreak of a mysterious virus in Wuhan City by the end of December 2019, when few hundred people with pneumonia and flu-like symptoms died. Researchers reported that the disease was contagious and in a matter of 3-4 months, the disease was transmitted throughout the globe like wildfire. On March 11, 2020, the World Health Organization (WHO) declared the Coronavirus outbreak as a global pandemic (Cucinotta & Vanelli, 2020).

The outbreak of this pandemic has already caused vast devastation worldwide with death, lockdown, unemployment, overwhelmed healthcare systems and failure of the Government in safeguarding lives. Considering all these damages of the outbreak, an attempt has been made to analyze the literature of the last three decades on Coronavirus using Bibliometrics. This type of analysis has been extensively performed to measure scientific activities in many fields.

COVID-19, an infectious disease is caused by a newly discovered coronavirus. People infected with the COVID-19 virus experience mild to moderate respiratory problems and can recover by home isolation with proper medication (WHO). The outbreak of the disease in December 2019 posed a serious turn and took the shape of an international pandemic within a very short span of time causing mass devastation.

Although by now, it is well known throughout the world that COVID-19 is very different and complicated from SARS and MERS but the scientific knowledge of COVID-19 is still at a nascent stage. There are several studies conducted through bibliometrics on a wide range of subjects. It is therefore important to understand the trends of scientific knowledge in this particular domain (Hossain, 2020). Bibliometric studies in healthcare are conducted to help in assessing the impact of a certain disease across the world, publication pattern over a period of time, most productive countries or institutes, prolific authors, collaboration patterns, etc., which further helps in decision making among researchers as in (Cruz-Calderón et al., 2015), (Chauhan, 2019), (Bundschuh et al., 2013) and many more. Taking into consideration the severity and complexity of the topic, the author selected 30 years as the timeline to understand how the disease has modified from the past as a study on Drone (Chauhan, 2019) for 50 years had been carried to understand its modification and usage patterns.

The data for this study has been obtained from the renowned database, WoS by Thomson Reuters for a period of 30 years from1989-2019. A total of 4917 documents were obtained. By using scientometric tools, an investigation was performed to assess the quality and quantity of research activity for the total number of published items, prolific authors in the field, type of research activities, journals with high citations, etc.

The term ‘Coronavirus’ (also accommodating COVID-19, Coronavirus (SARS-CoV), the Middle East respiratory syndrome Coronavirus (MERS-CoV) was taken and searched in the title, abstract and keyword indexes. The data were then analyzed further using MS Excel and Bibliometrix-R. The analysis has been done to extract the growth of publication, citations of publication, top journals and prolific authors and their organization.

Based on the analysis of data, 4917 documents were extracted in the form of articles, review papers, book chapters, proceedings, notes, etc. These 4917 documents were contributed by 14442 authors and were published in 711 sources and the average citation per document is 33.69.

Fig. 1 shows the year-wise growth of research publications on Coronavirus from 1989-2019. A total of 4917 articles studied during this period showed a progressive increase in number during the tenure of 30 years. With an average of 1280 publications or 26.03% of growth, the period from 2005-2009 can be marked to have published the highest number followed by the year 2015-2019 with 1153 or 23.45% publications.

Fig. 1. 
Year-wise growth of publication

Table 1 gives the characteristics of the growth of the publications studied for a time span of 30 years. Table 1 gives an analysis of the citations received by these 4,917 articles including the citations received per article and per year. The articles published in 2003 scored the highest number of citations (138.5 citations per article). This year was remarkable as World Health Organization announced that a new pathogen, a member of the Coronavirus family which was the cause of Severe Acute Respiratory Syndrome (SARS). The articles published during 2003-2005 also have an average citation of over 50 citations on average per paper.

Table 2 enlists 15 top-notch journals publishing on Coronavirus since 1989-2019. Different methodologies were adopted to assess the value of the journals publishing research articles. The top five most productive journals emanating from this analysis include Journal of Virology, Virology, Journal of General Virology, Virus Research, and Emerging Infectious Diseases. All these publications were started in 1989 except Emerging Infectious Diseases that published in this genre in 2003.

Among the top journals studied in this paper, the Journal of Virology published 759 articles, which is 15.44% of the total share of a number of articles during the study period of 30 years (1989-2019). It also received a huge number of citations (36,955) with h-index at 91 and g-index at 124. Journal impact factors for this paper is based on Journal Citation Report (JCR). JCR ranking for this journal stood at 4.368. Virology had a JCR ranking 3.374 followed by the Journal of General Virology (2.514) and the journal of Virus Research and journal of Emerging Infectious Diseases at 2.484 and 7.422 ranking, respectively. Journal of Virology received a total of 10697 citations for 279 articles and obtained h-index of 57 and g-index of 82 obtaining 3.374 JCR ranking. Journal of General Virology received a total of 4807 citations on 145 articles. It’s h-index was at 42 and g-index at 61. The journal of Virus Research received a total of 2,585 citations for 119 papers and journal of Emerging Infectious Diseases received a total of 4,687 citations for 114 papers. Journal of Virus Research received h-index of 30 and g-index of 41. Journal of Emerging Infectious Diseases received an h-index of 41 and g-index of 64.

JCR impact factor is a ratio between citations and recent citable items published. The impact factor of a journal is calculated by dividing the number of current year citations to the source items published in that journal during the previous two years.

Based on the total publication, top 20 author's contributions and research impact for the study period were analyzed in Table 3 along with their index factors including h-index, g-index and their total citation (TC).

All the authors have more than 50 publications and the top three prolific authors including Yuen KY, Enjuanes L and Perlman S are having more than 100 publications. Yuen KY has been found to be the most productive author with 114 papers which received a hooping (10,471 TC), (h-index = 51), (g-index = 102) and (m-index = 2.83) followed by Enjuanes Lwith111 articles that received a TC of 4,440, (h-index = 43), (g-index = 61) and (m-index = 1.34) followed by Perlman S(104 articles) and Drosten C(94 articles).Regarding the parameter of citation impact, Drosten C was more impactful with the second-highest number of citations (8,986 citations) for 94 papers followed by Chan KH with (7,820 citations) for 66 papers and Peiris JSM with 6,875 citations on 58 papers. However, all these authors had more than 1,000 TC.

Table 4 shows organization-wise contributions on Coronavirus. Top 20 organization along with their countries across the globe are presented. The highest five countries include the US with 1386 publications, Hong Kong with 791 followed by the Netherlands with 292 publications. India secured 4th position with 124 articles from the National Institute of Infectious Disease and China 5th with 100 articles from Fudan University.

Significant universities from the US include the University of Iowa, University of North Carolina, Vanderbilt University, Centres for Disease Control and Prevention, The University of Texas Medical Branch, University of Penn, University of South California, University of Texas, Ohio State University, Scripps Research Institute and Purdue University. The University of Hong Kong and Chinese University of Hong Kong were the top institutes in contributing to the publication of articles in the Corona Virus. Authors from Utrecht University and Leiden University from the Netherlands contributed significantly to the Corona virus.

Table 5 shows country-wise total citations and average article citations of articles on the Corona virus during the study period of 30 years. Top 15 countries with total citations along with their average citations per article.

The top five countries include the USA with 52405 total citations (TC), China followed with 26288 TCs and the Netherlands with 16009. Germany and the UK each had 12490 TC and 9033 TCs. However, the Netherlands had the highest average article citation per article with the highest number at 67.83 followed by Switzerland with 46.22 average article citation per article and Germany 43.67. The UK followed with 42.41 and the US with 38.76 average citations per article.

Top 20 articles cited during the study period of 30 years (1989-2019). The most cited articles were analyzed based on the total number of citations scores by these articles during the study period of 30 years in Table 6.

Out of 4,917 articles, the top five authors with high total citations include Ksiazek TG obtained the highest citations of 1823 and (TC per year = 101.2778) followed by Drosten C with 1,732 citations (TC per year = 96.2222) and Rota PA with 1,487 citations, Peiris JSM with 1,436 and Zaki AM with 1275 citation. However, articles by author Zaki AM in the journal New England Journal of Medicine received highest TC per year at 141.67.

Fig. 2 summarizes the complete analysis, of the top 20 authors along with their affiliation. These top 20 authors have the affiliation from 20 countries. A strong network is seen from the University of Hong Kong though a majority of them have the roots in the USA.

Fig. 2. 
Top 20 Authors from top 20 countries along with affiliation

Bibliometric methods use various mathematical and statistical measures which are quantitative in nature but they lead to qualitative features, such as publication patterns, prospecting research opportunities, author collaboration patterns, etc. Bibliometric studies often focus on a specialized subject matter and look after its publishing patterns. The patterns may include geographical or institutional aspects, performance indicators in the field for the time period under study, top institutes, country-level participation in publications and authorships. Different significant variants including h-index, g-index or m-index are also important indicators. The amount of international collaborations or co-authorships also play a significant part as it creates awareness among the scientific community. Through this study, an effort has been made to quantify research productivity during a period of 30 years.

Based on the WoS database, the characteristics of Coronavirus research output from 1989-2019 were investigated by the authors through bibliometric methods. The study demonstrated some interesting facts about the Coronavirus literature. In total, there were 4,917 documents contributed by 14,442 researchers in 711 sources. The articles published in 2003 scored the highest number of mean citations of 138.85. The Journal of Virology was the topmost journal. The maximum researchers were affiliated with the University of Hong Kong. A significant contribution has been seen from the organization USA, Hong Kong and the Netherlands. Ksiazek TG emerged as the most productive author with the highest citation and h-Index value.