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

TLDR

Low‑dose mRNA vaccines could increase dose availability and reduce reactogenicity, but it is unclear whether they elicit immune responses comparable to standard doses. The study compared immune responses in participants receiving 25‑μg versus 100‑μg mRNA‑1273 and in SARS‑CoV‑2–infected controls. Low‑dose Moderna induced durable T‑cell immunity comparable across ages and boosted by cross‑reactive T cells, while antibody and T‑cell responses matched natural infection but were roughly half the magnitude of high‑dose vaccination. Citation: Mateus et al.; STS.

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