Holistic Analysis of Coronavirus Literature: A Scientometric Study of the Global Publications Relevant to SARS-CoV-2 (COVID-19), MERS-CoV (MERS) and SARS-CoV (SARS)

Objectives: In late December 2019, a cluster of patients with pneumonia caused by an unknown pathogen was reported from Wuhan, Hubei Province, China. The pathogen has been identified as a novel coronavirus, severe acute respiratory syndrome 2 (SARS-CoV-2) and the disease has been named as coronavirus disease 2019 (COVID-19). The objective of this study was to perform the first holistic scientometric evaluation of coronavirus publications. Methods: Our main source for this study was Web of Science Collection database. All items published between 1980 and 2019 were included. A distribution map of global production in coronavirus literature and scientometric networks were generated. Results: The United States, China, Germany, the United Kingdom, and Netherlands were the most productive countries. Publications in coronavirus literature have been produced from almost every country in the world, except for some countries in Asia and Africa. Conclusion: While in the 1980s, the United States and developed countries from Europe were major source countries and the virus was identified only as an animal disease in the literature and its biological and genetic structure was investigated, in the 2000s, China became a major contributor of coronavirus literature because the SARS outbreak originated from southern China. Almost all most-cited publications in this period are related to SARS and the ACE2 protein.

I n late December 2019, a cluster of cases with pneumonia caused by an unknown etiology was reported from Wuhan, Hubei Province, China. 1 Later, the cause of the disease was identified as a novel betacoronavirus, the 2019 novel coronavirus (2019-nCoV). The disease was coined as coronavirus disease 2019 . Recently, the official name of the virus that causes COVID-19 has been announced by World Health Organization (WHO) as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). 2 Scientometrics, also known as "Science of science," is a popular statistical method analyzing scientific literature thoroughly in a certain field. 3 The academic literature lacks an in-depth scientometric study evaluating coronaviruses and disease caused by them. Herein, we aimed to perform a holistic scientometric assessment of the coronavirus literature.

METHODS
Our main source of this study was Web of Science (WoS, Thomson Reuters, New York, NY) Core Collection database. We preferred WoS as our main data source because it provides data analysis for publications and citations and allows the results to be sorted according to the number of citations. In addition, WoS attribution data are considered more reproducible and reliable than other databases, and WoS is used as the standard by certain official organizations. 4 We used keywords of "coronavirus," "SARS", "SARS-CoV", "MERS", "MERS-CoV", and "COVID-19" for our analysis. All items published between 1980 and 2019 were included, and documents produced in 2020 were excluded for our major analysis. A distribution map of global production of coronavirus literature was generated by a free Web source named GunnMap. 5 VOSviewer freeware was used to create scientometric networks. 6

General Features of Coronavirus Literature
A total of 13,833 documents indexed in WoS Core Collection between 1980 and 2019 were found in coronavirus literature, 7339 of which were open access. The peak year for publication was 2016 with 837 papers and 106 articles have been produced in 2020 so far. English was the major language of coronavirus literature (96.957%) followed by French, German, Spanish, and Chinese (0.802, 0.766, 0.289, and 0.231, respectively). Original articles covered 80.518% with 11,138 documents of all coronavirus literature followed by reviews, proceeding papers and editorials (8.545, 4.634, and 2.704%, respectively; Table 1). Virology, Veterinary Sciences, and Infectious Diseases were the most studied areas in literature ( Table 1).

Performances of the Countries, Authors, Institutions, and Sources
The United States of America (USA) ranked first in coronavirus literature with 4894 articles (35.379%) followed by China, Germany, the United Kingdom (UK) and the Netherlands (16.663, 6.701, 6.448, and 5.711%, respectively). Publications in coronavirus literature have been produced from almost every country in the world, except for some countries in Asia and Africa ( Figure 1). Yuen from the University of Hong Kong (China) was the most prolific author with 218 indexed papers (1.576%, Table 1). University of Hong Kong was also detected as the most productive institution in the literature with 534 publications (3.86%; Table 1

1990-1999
Coronavirus literature had 1674 documents indexed between 1990 and 1999. The United States, Germany, Canada, the United Kingdom, and the Netherlands were the most productive countries between 1990 and 1999 (44.265, 8.961, 8.303, 8.244, and 7.826, respectively). Lai from University of Southern California (USA) was the most prolific author with 70 documents. The Journal of Virology was the prominent source title in this decade with 226 articles (13.501%), and University of Southern California (USA) was the most contributor institution with 96 papers (5.735%). H-index was measured as 105 and published documents were cited 63,445 times in this period (53,214 without self-citations). The most cited document was an original article titled "Community Study of Role of Viral-Infections in Exacerbations of Asthma In 9-11-Year-Old Children" by Johnston et al. (Table 1). As we analyzed scientometric network analysis of coronavirus literature in this period the most indexed keywords were detected to be "coronavirus," "mouse hepatitis virus," "transmissible gastroenteritis virus," "rotavirus," and "cat" (Table 1).  Table 1). The most indexed keywords were detected to be "coronavirus," "SARS-CoV," and "spike protein" (Table 1). Scientometric network map of the most used keywords showed a starburst pattern in which the keywords of "coronavirus," "SARS," "SARS coronavirus," and "SARS-CoV" centered.

2010-2019
The decade of 2010s was the most active period of the literature with 6601 documents. Most documents (N = 4146; 62.8%) were open access and 80.7% of all items were original articles. The United States, producing 33.586% of all coronavirus literature, ranked first as ever, followed by China, Germany, Saudi Arabia, and The United Kingdom (22.406, 6.575, 6.454, and 6.166%, respectively). University of

DISCUSSION
It is important to analyze the coronavirus literature based on periods, because it helps us understand the progression of the disease. In the 1980s, the United States and developed countries from Europe were major source countries. During this period, the virus was identified only as an animal disease in the literature, and its biological and genetic structure was investigated. In the second decade we investigated (1990s), the United States and European countries stood out again and the coronaviruses started to be examined in terms of whether it affected the health of animals and people with asthma (Table 1). In fact, in this period, the effects of these   Table 1). The authors reported that species of bats were a natural host of coronaviruses closely related to those responsible for the SARS outbreak. In the conclusion paragraph of this manuscript, Li et al. suggested in-depth investigation of reservoir host distribution, animal-animal and human-animal interaction (particularly within the wet-market system), and analyzing genetic diversity of bat-borne viruses to avoid future outbreaks. 8 In April 2012, a novel lethal zoonotic pathogen, MERS-CoV, was identified in humans in Saudi Arabia and Jordan. A total of 2499 confirmed cases and 858 deaths (mortality rate, 34.3%) were reported from 27 countries. Outbreaks caused by human-human transition in Saudi Arabia in 2014 and South Korea in 2015 occurred. 9 In 2010s, Saudi Arabia became one of the major sources in coronavirus literature. Almost all most-cited articles were related to MERS in this period.
We found only one scientometric document relevant to coronavirus literature. It was a letter with limited data and no tables or images revealing scientometric networks. The authors reported that the United States and China had primary roles in the literature. 10

CONCLUSIONS
In late 2019, a novel coronavirus causing SARS-like pneumonia was identified. This novel virus was temporarily named as SARS-CoV-2 and the disease has been coined as COVID-19 by the WHO. 2 By the date of writing this study, a total of 167,682 confirmed patients and 6456 deaths were reported from 157 countries and territories, and the COVID-19 outbreak has been officially declared as pandemic. We hypothesized that the COVID-19 pandemic could be prevented if the suggestions of the articles previously published, such as that by Lie et al., were taken into consideration and the wetmarkets were completely closed to cut off the human-animal interaction. Scientometric studies should be performed in certain diseases that previously caused epidemics to prevent global spread in the future and to take urgent measures.