Age Is Just a Number: A Critically Important Number for COVID-19 Case Fatality

Type Journal Article Author David N. Fisman Author Amy L. Greer Author Ashleigh R. Tuite URL https://www.acpjournals.org/doi/10.7326/M20-4048 Publication Annals of Internal Medicine ISSN 0003-4819 Date 22/07/2020 Extra Publisher: American College of Physicians Journal Abbr Annals of Internal Medicine DOI 10.7326/M20-4048 Library Catalog acpjournals.org (Atypon) Abstract A pandemic, by definition, represents worldwide, simultaneous epidemics caused by a novel pathogen. The multinational nature of such an event inevitably leads to cross-national comparisons of epidemic growth, impact, and public health response. Such comparisons lend themselves to ecological research: For example, the apparent slower epidemic growth rates in countries that use bacilli Calmette–Guérin (BCG) vaccine has caused some researchers to assert that BCG vaccination may affect susceptibility to severe acute respiratory syndrome coronavirus 2 (1). Others have made similar observations about higher mean temperature and slower growth of the coronavirus 2019 (COVID-19) epidemic (2). These national-level comparisons are vulnerable to “ecological fallacy,” or attribution of individual-level outcomes to aggregate exposures (3). However, they also represent “unfair comparisons” (3), because the countries in question differ fundamentally on a confounder known to be associated with COVID-19 severity: age. Short Title Age Is Just a Number