Toxicologic Pathology Forum*: mRNA Vaccine Safety–Separating Fact From Fiction

SARS-CoV-2 spread rapidly across the globe, contributing to the death of millions of individuals from 2019 to 2023, and has continued to be a major cause of morbidity and mortality after the pandemic. At the start of the pandemic, no vaccines or anti-viral treatments were available to reduce the burden of disease associated with this virus, as it was a novel SARS coronavirus. Because of the tremendous need, the development of vaccines to protect against COVID-19 was critically important. The flexibility and ease of manufacture of nucleic acid–based vaccines, specifically mRNA-based products, allowed the accelerated development of COVID-19 vaccines. Although mRNA-based vaccines and therapeutics had been in clinical trials for over a decade, there were no licensed mRNA vaccines on the market at the start of the pandemic. The rapid development of mRNA-based COVID-19 vaccines reduced serious complications and death from the virus but also engendered significant public concerns, which continue now, years after emergency-use authorization and subsequent licensure of these vaccines. This article summarizes and addresses some of the safety concerns that continue to be expressed about these vaccines and their underlying technology.