Prevention of host-to-host transmission by SARS-CoV-2 vaccines

As the number of individuals vaccinated against SARS-CoV-2 rises worldwide, population-level data regarding the vaccines' ability to reduce infection are being generated. Randomised trials have shown that these vaccines dramatically reduce symptomatic COVID-19; however, less is known about their effects on transmission between individuals. The natural course of infection with SARS-CoV-2 involves infection of the respiratory epithelia and replication within the mucosa to sufficient viral titres for transmission via aerosol particles and droplets. Here we discuss the available data on the existing, approved SARS-CoV-2 vaccines' capacity to reduce transmissibility by reducing primary infection, viral replication, capacity for transmission, and symptomaticity. The potential for mucosal-targeted SARS-CoV-2 vaccine strategies to more effectively limit transmission than intramuscular vaccines is considered with regard to known immunological mechanisms. Finally, we enumerate the population-level effects of approved vaccines on transmission through observational studies following clinical trials and vaccine distribution in real-world settings.

Automated summary

As more people receive the SARS-CoV-2 vaccine worldwide, data is being generated to understand the vaccines' ability to reduce infection. Although randomized trials have shown that these vaccines greatly reduce symptomatic COVID-19, their effects on transmission between individuals are not well-known. This article discusses the available data on approved SARS-CoV-2 vaccines in reducing transmissibility by reducing primary infection, viral replication, transmission capacity, and symptomaticity. It also explores the potential of mucosal-targeted vaccine strategies to more effectively limit transmission compared to intramuscular vaccines. The population-level effects of approved vaccines on transmission are further examined through observational studies following clinical trials and vaccine distribution in real-world settings.