Background

With a total of 3,541,881 deaths among 170,360,315 confirmed cases [1] as of May 31st, 2021, the coronavirus disease 2019 (COVID-19) pandemic has placed a strain on health systems worldwide. According to the Organization for Economic Co-operation and Development, an estimated 7 billion dollars, dedicated to COVID-19 research, were unlocked worldwide in the first 9 months of 2020 [2]. Linked to that, major collaborative efforts have been launched to urgently address COVID-19 related medical issues [3, 4], sometimes at the expense of non-COVID-19 research [5]. Some medical fields have experienced a decrease in funding allocation and publications [6], which had potentially affected patient care outside of COVID-19. For instance, the pandemic has seriously impacted cancer patients with treatment delays and reduced access to healthcare [7]. Similarly, it has had detrimental effects on organ allocation and transplantation worldwide [8], with a significant reduction in the number of transplanted organs per day, with disastrous consequences for patients whose lives depend on getting transplanted.

Overall, there has been a substantial redistribution of resources which has significantly impacted the non-COVID-19 medical research worldwide [9], including clinical trials [10, 11]. In addition, leading scientists have voiced concerns about science expediency [12] and the lowering of scientific standards [13, 14]. Together, these phenomena could have played a significant role on the dynamics of publication and worldwide medical research.

Moreover, recent research has reported a rising number of authors in COVID-19 publications [15], especially in case reports [16, 37]. Overall, innovations and discoveries have been brought and may help advancing medical research.

Although the worldwide population is progressively getting vaccinated, the COVID-19 pandemic still exerts a very harmful effect on many countries [38, 39]. In addition, the rise of many variants may challenge the efficacy of vaccines [40, 41] and delay the decrease in the number of cases and deaths. Accordingly, the medical research beyond COVID-19 is likely to be impacted in the long run. As such, we urge researchers to help continuing the evaluation on how health systems, medical research and resources are managed in pandemic time, as we attempted to accomplish in the present study.

Limitations

Several limitations should be acknowledged. First, due to the very high number of studies, the references were not assessed by two independent reviewers. However, after the screening completion, three reviewers randomly checked 20% of the references for each reviewer, and a second screening was performed if more than 3% inconsistencies were observed. Second, for the same reason, we had to restrict the analyses on the highly cited medical journals only. This may have induced a selection bias, as the editorial strategies might be different in lower-impact journals. However high-impact journals likely reflect and drive the trends in publications and are therefore relevant examples to analyze the impact of the pandemic on medical research. Third, we investigated the impact of the COVID-19 pandemic on non-COVID-19 research by focusing on the publication dynamics, the publication type, and the phenomenon of author multiplicity. Critically appraising all studies would have been ideal and enhanced our demonstration; but this would have been a gigantic work that cannot be accomplished in such study design.

Conclusion

To conclude, in this meta-research gathering original articles, research letters and case reports published in high-impact medical journals, we have shown the heterogeneity in the publication dynamics, and measured the impact of the COVID-19 pandemic in the production of non-COVID-19 studies. This study revealed how medical journals adapted to the pandemic, as some maintained the production of non-COVID-19 studies, and some decreased the production of non-COVID-19 studies. Last, we have identified an author multiplicity phenomenon in COVID-19 studies.