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.