Geographical distribution and international collaboration
A total of 23,969 publications included the authors’ addresses. We plotted a global geographical distribution map of publications during different stages of the epidemic and the reported cases of SARS, MERS and COVID-19 (Fig. 2).
In the period from 1991 to 2002, 49 countries were involved in coronavirus research. The USA produced the most publications (802), followed by the UK (126), the Netherlands (123), Germany (122) and Canada (117); these were the five most productive countries. Research locations were mainly distributed across North America, Europe and Japan. Eighty-three countries participated in coronavirus research from 2003 to 2011. The number of publications from China varied from 4 in the period from 1991 to 2002 to 2,469, at which point China ranked first, followed by the USA (1,907), Canada (517), the UK (378) and Germany (354). Unlike in North America and Europe, the number of publications from Asian countries (particularly China, Singapore and South Korea) and Australia greatly increased, as these countries were affected by SARS. According to World Health Organization (WHO) situation reports, there were reported cases of SARS in 32 countries and territories from November 2002 to July 2003, while Asian countries (especially China, Singapore and Vietnam) and North America (especially Canada and the USA) were affected more severely [8]. In the period from 2012 to 2019, 113 countries issued related publications. The USA ranked first (1,759), followed by China (1,502). Saudi Arabia varied from 11 publications in the period from 2003 to 2011 to 432 publications, ranking 3rd. Moreover, South Korea also devoted more attention to this topic, ranking 6th (346). In addition to North America, Europe, China and Japan, the Middle East (especially Saudi Arabia, Egypt, the United Arab Emirates, Iran and Jordan) and South Korea clearly produced more publications. According to the WHO situation reports, MERS spread to 27 countries from 2012 to 30 June 2018; the Middle East and South Korea were the main epidemic territories, and Saudi Arabia accounted for 83% of cases [9]. In 2020, 144 countries contributed to coronavirus research. The USA ranked first (3,078), followed by China (2,782), Italy (1,518), the UK (1,349) and Canada (588). The number of publications rapidly increased, and the research locations became more diverse following the dramatic and persistent impact of the COVID-19 pandemic.
The proportion of publications that were internationally co-authored varied from 0.45% in 1991-2019 to 10.34% in 2020. Collaborations between countries and territories became more common after the SARS and MERS outbreaks but were clearly enhanced during the COVID-19 outbreak (Fig. 3). In the period from 1991 to 2019, the USA occupied the central position in the collaboration network. The USA collaborated with China and the UK most closely, while most other countries and territories were more likely to produce single-country publications. In 2020, we found that the USA, China, the UK, Italy, Canada, Australia and Germany contributed to more internationally collaborative publications. There was a striking increase in intensive collaborations, with more diversity in the countries and territories participating in the cooperation and communication (Fig. 4).
Our results reveal some interesting findings. First, research locations became more diverse due to the epidemics of SARS, MERS and COVID-19; of the three epidemics, the COVID-19 epidemic had more widespread and powerful effects on countries and territories with scant warning. COVID-19 is a substantial global public health threat, with severe economic implications. The COVID-19 pandemic has stimulated research on traceability analyses, transmission, diagnostic methods, epidemiology, treatments, prevention, and containment of the disease [10]. Patients early in the outbreak provided large sample sizes for studies of the clinical characteristics of COVID-19 and factors that could be used to predict the spread of COVID-19. Second, countries and territories engaged in more international collaborations and communication to cope with the epidemic, and COVID-19 substantially stimulated advancements in research. Scientists from different countries worldwide have strengthened their collaborative partnerships and launched joint research projects investigating methods of preventing the spread of the disease and controlling the epidemic.