It is very exceptional that a new disease becomes a true pandemic. Since its emergence in Wuhan, China, in late 2019, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the virus that causes COVID-19, has spread to nearly all countries of the world in only a few months. However, in different countries, the COVID-19 epidemic takes variable shapes and forms in how it affects communities. Until now, the insights gained on COVID-19 have been largely dominated by the COVID-19 epidemics and the lockdowns in China, Europe and the USA. But this variety of global trajectories is little described, analysed or understood. In only a few months, an enormous amount of scientific evidence on SARS-CoV-2 and COVID-19 has been uncovered (knowns). But important knowledge gaps remain (unknowns). Learning from the variety of ways the COVID-19 epidemic is unfolding across the globe can potentially contribute to solving the COVID-19 puzzle. This paper tries to make sense of this variability—by exploring the important role that context plays in these different COVID-19 epidemics; by comparing COVID-19 epidemics with other respiratory diseases, including other coronaviruses that circulate continuously; and by highlighting the critical unknowns and uncertainties that remain. These unknowns and uncertainties require a deeper understanding of the variable trajectories of COVID-19. Unravelling them will be important for discerning potential future scenarios, such as the first wave in virgin territories still untouched by COVID-19 and for future waves elsewhere.
- public health
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Contributors WVD, RD, EW and YA conceived and designed the study. RD, GV, YA and WVD searched the literature and screened for new emerging evidence. WVD, RD and YA drafted successive versions of the manuscript and coordinated inputs from all coauthors. YA, SA, KV, BI, RvdP and HK contributed to writing the manuscript. AD, J-PD, PI, SVdB, DN, GB, IVE, MAAA, JAK, VDB, KB, PA, AK, SA-A, NSP, J-JM-T, PM and SA-M reviewed successive versions of the manuscript and oriented it, with a field-based and local gaze from Guinea, Benin, Cambodia, Belgium, India, the UK, Mali, Canada, Burkina Faso, Germany, the USA, Guinea-Bissau, the Democratic Republic of Congo, Yemen and Australia. All authors commented on subsequent versions of the manuscript and approved the final version. WVD attests that all listed authors meet authorship criteria and that no others meeting the criteria have been omitted.
Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.
Competing interests None declared.
Patient consent for publication Not required.
Provenance and peer review Not commissioned; externally peer reviewed.
Data availability statement No additional data are available.
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