Variation (astronomy)
Observational study
Coronavirus disease 2019 (COVID-19)
Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)
2019-20 coronavirus outbreak
Retrospective cohort study
Demography
Medicine
Statistics
Mathematics
Virology
Sociology
Physics
Disease
Pathology
Outbreak
Astrophysics
Infectious disease (medical specialty)
Internal medicine
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