How to interpret the total number of SARS-CoV-2 infections

• Authors: Kayoko Shioda, Emory University; Benjamin Lopman, Emory University
• Journal Title: LANCET
• Volume: Volume 399, Number 10344
• Publisher: ELSEVIER SCIENCE INC | 2022-06-25, Pages 2326-2327
• Type of Work: Article | Final Publisher PDF
• Publisher DOI: http://doi.org/10.1016/S0140-6736(22)00629-8
• Subjects: Health Sciences, Epidemiology; Health Sciences, Public Health
• Keywords: Science & Technology; Life Sciences & Biomedicine; Medicine, General & Internal; General & Internal Medicine

Abstract

Counts of reported cases have been the key metric to monitor the COVID-19 pandemic. However, since the beginning, it has been clear that reported cases represent only a fraction of all SARS-CoV-2 infections.1 In The Lancet, COVID-19 Cumulative Infection Collaborators, writing on behalf of the Institute for Health Metrics and Evaluation, report a comprehensive set of global and location-specific estimates of daily and cumulative SARS-CoV-2 infections and the proportion of the population infected for 190 countries and territories up to Nov 14, 2021.2 For this, the authors used a novel approach, combining data from reported cases and deaths, excess deaths attributable to COVID-19, hospitalisations, and seroprevalence surveys to produce more robust estimates in an attempt to minimise biases. According to COVID-19 Cumulative Infection Collaborators findings, a staggering number of people, 3·39 billion (95% uncertainty interval 3·08–3·63) or 43·9% (39·9–46·9) of the global population, are estimated to have been infected one or more times between March, 2020, and November, 2021. Remarkably, this was before the highly transmissible omicron (B.1.1.529) variant swept the globe. These estimates of total infections are wildly different from the number of reported cases, which stood at 254 million as of Nov 14, 2021.3