Population immunity and vaccine protection against infection

• Type of Material: Article
• Authors: Eyal Leshem, Chaim Sheba Medical Center; Benjamin Lopman, Emory University
• Language: English
• Date: 2021-05-06
• Publisher: Elsevier Science Inc.
• Publication Version: Final Published Version
• Copyright Statement: © 2021 Elsevier Ltd. All rights reserved.
• License: Creative Commons Attribution 4.0 International
• Final Published Version (URL): http://dx.doi.org/10.1016/S0140-6736(21)00870-9
• Title of Journal or Parent Work: The Lancet
• Volume: 397
• Issue: 10286
• Start Page: 1685
• End Page: 1687
• Grant/Funding Information: None declared
• Keywords: Life Sciences & Biomedicine; Medicine, General & Internal; Science & Technology; BNT162B2; COVID-19; SARS-COV-2 Infection; General & Internal Medicine
• Research Categories: Health Sciences, Epidemiology; Health Sciences, Public Health; Health Sciences, Immunology

Abstract

Vaccines act by two broad main mechanisms. They can block infection occurring entirely or they can halt the progression to symptoms after infection occurs.1 The most direct pathway to population immunity is the first mechanism, also known as sterilising immunity. Because, if a person cannot get infected, they cannot transmit. For this reason, there has been tremendous interest in determining the extent to which COVID-19 vaccines block infection. By now, it is clear that the vaccines are remarkably effective against severe disease and some tantalising preliminary findings have suggested substantial protection against infection.2, 3, 4 However, studies to date have mostly been from relatively small subgroups in trials, are ecological in design, or used proxies for asymptomatic infection rather than directly swabbing and testing individuals.