Low-dose mRNA-1273 COVID-19 vaccine generates durable memory enhanced by cross-reactive T cells

Abstract

A smaller-dose jab does the job Low-dose messenger RNA (mRNA) vaccines potentially allow health providers to administer more doses from a limited vaccine supply and can be less reactogenic. Whether low-dose COVID-19 mRNA vaccines generate immune responses comparable to currently approved doses remains an open question, however. Mateus et al . report the results of a clinical trial comparing patients who received a 25-μg mRNA-1273 (Moderna) COVID-19 vaccine to 100-μg mRNA-1273 COVID-19 vaccinees and severe acute respiratory syndrome coronavirus 2–infected individuals. The low-dose Moderna vaccine generated long-lived T cell immunity that was equivalent between younger and older patients and that could be enhanced by the presence of cross-reactive T cells. Moreover, antibody and T cell responses induced by the low-dose vaccine were comparable to natural infection and about half as strong as those seen with high-dose vaccination. —STS