A new survey of highly cited COVID-19 research papers shows the scientific literature on the novel coronavirus rose at an astronomical pace, from just 14 studies in January and February 2020 to 1,292 studies in November to December 2021. The study is published in JAMA Network Open.
The cross-sectional study surveyed global publications from January 2020 to December 2022 through Essential Science Indicators (ESI) and Web of Science (WOS) Core Collection databases. Studies were evaluated bimonthly through the study period, and the number of publications by research field, country, and institutional affiliation were noted by authors.
COVID-19 brought a glut of scientific literature, especially through preprint servers such as medRxiv and bioRxiv, which post studies before they have undergone peer review.
"The total number of COVID-19–related publications, including preprints, has increased dramatically and now exceeds 350,000 studies" the authors said.
The total number of COVID-19–related publications ... has increased dramatically and now exceeds 350,000 studies.
In addition to preprint servers, a citation analysis of studies published in predatory journals found that 60% of publications had not attracted any citations and 38% were cited only up to 10 times. To combat this, the present study authors wanted to analyze highly studied papers that have received a considerable number of citations in the previous 2 months, placing them in the top 0.1% of studies in the same field.
The top research field of highly citied studies was clinical medicine, followed by social sciences, psychiatry, and immunology.
The top countries for publication were the United States, the United Kingdom, China, Israel, and Canada.
More than 1,000 studies published at end of 2021
After the peak of 1,292 studies in November to December 2021, publication entered a downward trend until reaching 649 studies in November to December 2022.
Between July and August 2020, the most highly cited studies were published in China, followed by the United States (138.3 studies vs 103.7 studies, respectively). In September 2020, the United States overtook China in publishing highly citied studies (159.9 studies vs 157.6 in September to October 2020).
"Subsequently, the number of highly cited studies per 2-month period published by China declined (decreasing from 179.7 studies in November to December 2020 to 40.7 studies in September to October 2022), and the UK produced the second largest number of such studies in May to June 2021 (171.3 studies)," the study authors wrote.
The shift from China to UK and US-dominant studies was also demonstrated by a shift in top institutional affiliations for publications: In May to June 2020 the top five highly cited studies were from China (Huazhong University: 14.7 studies; University of Hong Kong: 6.8 studies; Wuhan University: 4.8 studies; Zhejiang University: 4.5 studies; Fudan University: 4.5 studies).
In November to December 2022, the top five institutions were US- and UK-based (Harvard University: 15.0 studies; University College London: 11.0 studies; University of Oxford: 10.2 studies; University of London: 9.9 studies; Imperial College London: 5.8 studies).
"Changes in distribution, top affiliations, and research fields of highly cited studies suggest a gradual shift in interest in COVID-19 research toward more diversified and broader research areas," the authors concluded. "Based on results of this investigation, we expect a sustained reduction in the number of highly cited studies on COVID-19."
