*Free* COVID-19 vaccine breakthroughs and boosters

In a Perspective, Ravindra Gupta and Eric Topol discuss COVID-19 vaccine efficacy in the context of breakthrough infections and the emergence of new variants. Although no vaccine protects against all infections, very few achieve such a high level of protection as that of the current, two-dose messenger RNA (mRNA) vaccines developed to combat SARS-CoV-2. In extensive clinical trials – among the largest ever conducted – COVID-19 mRNA vaccines were found to elicit high levels of protection against symptomatic disease. However, continued research has shown that this protection wanes over time, particularly in older individuals and the immunocompromised. More recently, and in response to increasing vaccine breakthrough infections and the prevalence of new SARS-CoV-2 variants, research suggests that a third, booster dose can restore vaccination effectiveness to more than 90%. Here, Gupta and Topol review recent studies on COVID-19 vaccine breakthrough infections and the efficacy of booster doses in protecting against SARS-CoV-2 variants, such as Delta. The authors conclude that, while boosters are important, and may remain so for a while, nonpharmaceutical interventions, such as mask-wearing and social distancing, not only help to reduce COVID-19 cases but also limit the opportunity for the emergence of variants that can evade immunity.