key: cord-0921133-3npk3u5t authors: Dehghanbanadaki, Hojat; Seif, Farhad; Vahidi, Yasmin; Razi, Farideh; Hashemi, Ehsan; Khoshmirsafa, Majid; Aazami, Hossein title: Bibliometric analysis of global scientific research on Coronavirus (COVID-19) date: 2020-05-23 journal: Med J Islam Repub Iran DOI: 10.34171/mjiri.34.51 sha: 5600fd1a08dec8541e111dee07e5eeeb017403f3 doc_id: 921133 cord_uid: 3npk3u5t Background: Since the outbreak of the novel coronavirus disease from Wuhan, China, in early December 2019, many scientists focused on this infection to find a way to deal with it. Due to the dramatic scientific growth in this field, we conducted a scientometric study to gain a better understanding of the scientific literature on COVID-19. Methods: We extracted all COVID-19 documents indexed in the Scopus from December 1, 2019, to April 1, 2020, without any language limitation and determined their bibliometric characteristics, including document type, open accessibility status, citation counting, H-index, top cited documents, the most productive countries, institutions and journals, international collaboration, the most frequent terms and keywords, journal bibliographic coupling and cocitations. Results: A total of 923 documents on COVID-19 were retrieved, of which 418 were original articles. All documents had received 2551 citations with an average citation of 2.76 per document and an h-index of 23. China ranked first with 348 documents, followed by the United States (n = 160). The Lancet and BMJ Clinical Research Ed published the most documents (each with 74 documents) and 2 institutions (University of Hong Kong and Huazhong University of Science and Technology) ranked first in this regard. In addition, the present study analyzed the top 25 highly-cited documents (those that had received 70% of all citations). Conclusion: This study highlighted the focused subjects on various aspects of COVID-19 literature such as pathogenesis, epidemiology, transmission, diagnosis, treatment, prevention, and its complications. In early December 2019, an outbreak of viral infection associated with pneumonia was initiated in Wuhan, Hubei Province, China (1, 2) . Severe acute respiratory syn-drome-Coronavirus 2 (SARS-CoV2) was identified as the cause of COVID-19, which was characterized by asymptomatic to severe infections in respiratory and gastrointeshttp://mjiri.iums.ac.ir Med J Islam Repub Iran. 2020 (23 May); 34:51. 2 tinal systems, kidneys, and heart (3) . Since the outbreak of COVID-19 worldwide, the number of cases has risen dramatically. Due to the rapid spread of COVID-19, the WHO has announced it as an urgent public health concern (4). Thus, the present study aimed to conduct a bibliometric analysis on COVID-19 articles worldwide from December 1, 2019 to April 1, 2020 to achieve the following goals: (a) to analyze the highly-cited articles in this field, (b) to present top countries, institutions, and journals, (c) to map the co-occurrences and keywords related to COVID-19, (d) to map co-contributions' network among countries, and (e) to map the bibliographic coupling and cocitation of journals for guiding other researchers about the direction of future COVID-19 articles. In this bibliometric study, we extracted all COVID-19 disease documents indexed in the Scopus from December 1, 2019, to April 1, 2020, without considering any language limitation. We searched the following queries in the Scopus database: (sars2) OR (sars-2) OR ("SARS 2") OR ("novel corona virus pneumonia") OR ("new human coronavirus") OR ("2019 novel coronavirus") OR ("2019 novel coronavirus infection") OR ("novel coronavirus") OR ("new coronavirus") OR ("severe acute respiratory syndrome coronavirus 2") OR ("sudden acute respiratory syndrome coronavirus 2") OR ("China coronavirus") OR ("Wuhan coronavirus") OR ("Wuhan seafood market pneumonia virus") OR (covid-19) OR ("COVID19 virus") OR ("Coronavirus disease 2019") OR TITLE-ABS ("coronavirus disease-19") OR ("Coronavirus disease 2019 virus") OR ("SARS-CoV-2") OR ("2019-nCoV") OR ("2019-nCoV disease") OR ("2019-nCoV infection"). Through this search strategy, 923 documents related to COVID19 were retrieved and different bibliometric aspects of all of these documents were investigated, which included document type, open accessibility of documents, citation counting, average citations per document, Hindex, top cited documents, document distribution around the world, the most productive countries, institutions and journals, collaboration between countries, the most frequent terms in the titles and abstracts, the most applying keywords, bibliographic coupling, and cocitations of journals. Following the completion of data extraction, we exported all data into Microsoft Excel for statistical analysis and ranking various bibliometric indices, including top cited documents, top countries, institutions, and journals. We used GunnMap 2 (http://lert.co.nz/map/) to illustrate the worldwide distribution of documents and VOSviewer software (version 1.6.13) (5) to visualize the connection between terms, keywords, countries, and the rainbow density map of bibliographic coupling and journal cocitation. The bibliographic coupling of journals in the literature of COVID-19 reveals how many COVID-19 articles of 2 journals had been bibliography coupled. In other words, when 2 articles cite the same document in their bibliographies, they are bibliographically coupled; thus, the journal cocitation analysis indicates the number of COVID-19 articles cocited in 2 given journals (6) . Through searching in the Scopus database, we extracted 923 documents written about COVID-19 from its emergence to April 1, 2020. Almost half (n = 418) of the retrieved documents were original articles and the remaining were 151 letters, 134 notes, 116 editorials, 75 reviews, 14 errata, 14 short surveys, and 1 data paper. Among all documents, 775 (83.96%) were open access. The total citations to all documents were 2551 times with average citations per document of 2.76 and h-index of 23. The total number of citations of original articles and reviews (n = 493) was 1895, with an average citation of 3.84 per document and h-index of 19 . The global distribution of COVID-19 documents is depicted in Figure 1 . In addition, Table 1 lists the first top 10 countries in the number of COVID-19 documents as well In addition, to illustrate the international collaboration between all 125 countries that published COVID-19 documents, we considered the countries with at least 5 documents (n = 32). We demonstrated the international collaboration network between these 32 countries in Figure 2 . States 160 2 Italy 105792 12430 3 United Kingdom 80 3 Spain 94417 8189 4 Italy 47 4 China 82638 3321 5 Canada 44 5 Germany 67366 732 6 Hong Kong 35 6 France 51477 3514 7 Germany 34 7 Iran 47593 3036 8 France 33 8 United Kingdom 25154 1789 9 Switzerland 31 9 Switzerland 16108 373 10 Australia 26 10 Turkey 13531 214 10 South Korea 26 Fig. 2 . The international collaboration network between the 32 countries with at least 5 COVID-19 documents is indicated. Through this network mapping, we realized there were a total of 241 collaborations with the strongest collaboration link between China and the United States. The color of each country represents the number of average citations per document that has been received by them and the size of each node represents the number of publications that has been published by that country. The first top 10 institutions affiliated with the retrieved documents are depicted in Table 2 that shows authors from The University of Hong Kong and Huazhong University of Science and Technology published most documents on this new emerging virus. We also ranked the journals by which these documents have been published and we realized that most of these documents were published in highly prestigious journals (Table 3) , including the Lancet (n = 74 documents), BMJ Clinical Research Ed (n = 74 documents), and Journal of Medical Virology (n = 47 documents). The citation counting of all documents on COVID-19 discovered that many researchers were interested in 25 documents listed in Table 4 . Zhejiang University School of Medicine 16 9 Zhongnan Hospital of Wuhan University 16 10 Zhejiang University 15 10 University of Toronto 15 Journal of Infection 12 9 New England Journal of Medicine 12 10 Nature 11 In other words, these 25 documents received the most citations among all documents (1784 times which comprise almost 70% of all citations) and they ranged from 21 to 250 citations. These documents consisted of 18 original articles, 3 letters, 2 reviews, 1 editorial, and 1 note, of which 7 were published in the Lancet, 5 in the New Eng- (2) on January 24, 2020 and was about the clinical characteristics of COVID-19 infected patients. They reported the symptoms, signs, laboratory findings, imaging findings, underlying diseases, and complications of 41 infected patients and concluded that COVID-19 resulted in severe acute respiratory distress syndrome leading to a higher probability of ICU cases and death. The second document in this list was a case-control study by Zhu N et al (7) published in the New England Journal of Medicine on February 20, 2020 and received 180 citations until the date of data extraction. This study used high-throughput sequencing technology and real time reverse transcription PCR to determine the etiology of a cluster of patients with unknown origin pneumonia linked to the Huanan seafood wholesale market in Wuhan, China. They reported that this novel infection was caused by the seventh member of the coronavirus family. The third study by Li Q et al (8) was published in the New England Journal of Medicine on March 26, 2020, and revealed that although this novel coronavirus infected humans through zoonotic exposure, the outbreak of this infection was initiated by human to human transmission in Wuhan since the mid-December 2019. In this section, we investigated the terms used in the title and abstract of all COVID-19 documents and the keywords to discover the hotspot of this topic in the documents. The most frequent terms were COVID (n = 983 repeats), patient (n = 741 repeats), SARS-CoV (n = 593 repeats), China (n = 497 repeats), case (n = 464 repeats), nCoV (n = 417 repeats), outbreak (n = 355 repeats), infection (n = 344 repeats), novel coronavirus (n = 324 repeats), Wuhan (n = 269 repeats), Coronavirus (n =243 repeats), virus (n = 204 repeats), pneumonia (n = 195 repeats), Coronavirus disease (n = 170 repeats), treatment (n = 162 repeats), transmission (n = 158 repeats), study (n = 156 repeats), data (n = 151 repeats), country (n = 137 repeats), and epidemic (n = 136 repeats). Next, we visualized the connection network of terms applying at least 15 times in the titles and abstracts. Accordingly, 168 terms of all 8078 terms were entered into the network and clustered into 4 groups, which are demonstrated with different colors in Figure 3 . The most frequent terms in each cluster are COVID (blue), SARS-CoV (red), patient (green), and infection (yellow), respectively. Similarly, the counting of author keywords revealed that the most co-occurrence keywords in COVID-19 documents are COVID-19 (n = 139 repeats), Coronavirus (n = 117 repeats), SARS-CoV-2 (n = 100 repeats), 2019-nCOV (n = 86 repeats), pneumonia (n = 34 repeats), epidemiology (n = 31 repeats), SARS (n = 24 repeats), novel Corona virus (n = 23 repeats), Wuhan (n = 22 repeats), outbreak (n = 21 repeats), infection (n = 18 repeats), SARS-CoV (n = 17 repeats), epidemic (n = 13 repeats), Coronavirus dis- Fig. 3 . The connection network of terms applying at least 15 times in the titles and abstracts. A total of 168 terms of all 8078 terms were entered into this network and clustered into 4 groups, which are shown with different colors. The most frequent terms in each cluster are COVID (blue), SARS-CoV (red), patient (green), and infection (yellow), respectively. 7 ease 2019 (n = 12 repeats), China (n = 12 repeats), MERS (n = 10 repeats), virology (n = 9 repeats), 2019 novel Coronavirus (n = 9 repeats), acute respiratory disease (n = 8 repeats), MERS-CoV (n = 8 repeats), transmission (n = 8 repeats), and diagnosis (n = 8 repeats). To visualize the connection network between author keywords, we considered only keywords with at least 5 co-occurrences and found out that 38 of 786 keywords were entered into the network and clustered into 6 groups (Fig. 4) . The most frequent keywords in each cluster are 2019-nCOV (red), Coronavirus (green), COVID-19 (dark blue), epidemiology (yellow), novel Corona virus (purple), and SARS-CoV-2 (light blue), respectively. The bibliographic coupling of journals in the literature of COVID-19 reveals how many COVID-19 articles of 2 journals had been bibliography coupled. In other words, when 2 articles cite the same document in their bibliographies, they are bibliographically coupled. Figure 5 shows the bibliographic coupling map of journals with at least 5 COVID-19 documents. Out of 308 journals, 41 met this threshold and 32 constructed the largest coupling network (Fig. 5) . In addition, the results of journal cocitation analysis indicates the number of articles that cocited the COVID-19 articles of 2 given journals. In this regard, we visualized the cocitation rainbow density of journals with at least 20 citations in the literature of COVID-19 (Fig. 6 ). In this study, we aimed to provide the perspective of COVID-19 documents in the world and identify our current position in the publication on this novel Coronavirus. We illustrated the hotspots of research on this topic so far and determined the origin of these documents from which countries, institutions, journals, and authors have arisen. This novel virus from the seventh membrane of the coronavirus family originated from Wuhan, Hubei Province, China, in early December 2019, causing a cluster of pneumonia with an unknown etiology that almost all patients linked to the Huanan seafood wholesale market (9) . The WHO named this virus as COVID-19 on February 11, 2020, and declared it as a pandemic on March 11, 2020 (10) . Since the emergence of COVID-19, the number of publications on this novel coronavirus has grown rapidly and different aspects of this infection such as epidemiology, pathogenesis, transmission, prevention, treatment, complications, prognosis, etc, attract much interest. Also, many promising documents have been published to date, most of which having been accepted and released by prestigious journals like the Lancet, BMJ Clinical Research Ed, the Journal of Medical Virology, the Euro Surveillance: European Communicable Disease Bulletin, and JAMA. We also observed that most of the top cited articles have been published in these journals. In addition, about 84% of the documents in this field were open access, with the purpose of understanding this novel infection sooner and decreasing this serious health threat in humankind. The country analysis based on the COVID-19 confirmed cases and the COVID-19 documents revealed that 7 out of top 10 countries with the most COVID-19 positive cases also worked the most in producing scientific documents and finding a solution for this pandemic. Spain, Iran, and Turkey which listed in the top countries with the most COVID-19 positive cases should pay more attention to this statistics in their policies. The analysis of the most frequent keywords applying in the literature of COVID-19 revealed some hotspots of focus during the study period. For example, this novel virus has been used under different names in this area, including COVID-19, Coronavirus, 2019-nCoV, SARS-CoV-2, and 2019 novel Coronavirus. In addition, during this time many studies have been conducted on the pathogenesis, epidemiology, transmission, and diagnosis of this virus; eg, (1) the similarity between this virus and other viruses from the Coronavirus family, such as SARS (severe acute respiratory syndrome) and MERS (Middle East respiratory syndrome); (2) the role of quarantine for the infection control of COVID-19 outbreak; (3) the diagnostic ability of CT scan (computed tomography);(4) ARDS (acute respiratory distress syndrome) complication; and (5) the status of this virus in the world as an epidemic which after a while changed into a pandemic. Interestingly, angiotensin-converting enzyme 2 (ACE2) is the only substrate in this network, suggesting its potential effect on the novel Coronavirus disease. ACE2 plays a critical role in the renin-angiotensin system (RAS) through which converts the angiotensin (Ang) I into Ang (1-9) and Ang II into Ang (1-7), respectively (11, 12) , and accordingly contributes to cardiovascular diseases such as coronary artery disease, hypertension, congestive heart failure, and myocarditis (13) . Many studies suggested that this enzyme could be a potential target in Influenza infection (H1N1, H7N9 and H5N1), inducing acute lung injury (14) (15) (16) and Coronavirus infection (SARS, HCoV-NL63 and 2019-nCoV) mainly through binding to the viral spike glycoprotein, which was a highly-focused subject in our bibliometric analysis on the most frequent terms in the literature of 2019-nCoV (17) (18) (19) (20) . Therefore, ACE2 could be targeted to manage COVID-19 disease in future studies. However, some bibliometric studies on COVID-19 have been conducted so far (21) (22) (23) included fewer COVID-19 documents than ours due to earlier data extraction or the use of other databases. Therefore, this study provided the comprehensive perspective of the COVID-19 documents indexed in Scopus to date. Chahrour M et al (21) conducted a bibliometric analysis on 564 documents on COVID-19 that had been published until March 18, 2020. They reported that China and the United States published most of these documents (377 and 39 documents, respectively) and Singapore ranked first based on the number of the documents per million persons (n = 1.069). Hossain MM (22) also conducted a bibliometric analysis on 422 COVID-19 documents indexed in Web of Science (WoS) core collection until April 1, 2020 and reported that China, the United States, the United Kingdom, Italy, and Canada produced the most documents on COVID-19 (185, 68, 36, 23 and 23 articles, respectively). In addition, top journals with the most COVID-19 documents were British Medical Journal (n = 47), the Lancet (n = 37), Eurosurveillance (n = 22), and Journal of Medical Virology (n = 22). We found that their findings based on the searching in WOS database are consistent with the results of our analysis on the documents indexed in Scopus. Since the emergence of COVID-19, many countries, journals, institutions, and researchers focused on this topic, which led to the rapid growing publications on this area of literature. To date, China, the United States, and the United Kingdom had the most scientific performance as well as international collaborations on COVID-19 research. The most published documents on COVID-19 were open access and were published in prestigious journals with high impact factors, including the Lancet, BMJ Clinical Research Ed, and Journal of Medical Virology. In addition, the present bibliometric analysis on COVID-19 literature shows the focused subjects in various aspects of this infection such as pathogenesis, epidemiology, transmission, diagnosis, treatment, prevention, and its complications. 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Available at SSRN 3547824 Coronavirus disease 2019: a bibliometric analysis and review The authors declare that they have no competing interests.