Study suggests those who had COVID-19 may only need one vaccine dose

People who have recovered from COVID-19 had a robust antibody response after the first mRNA vaccine dose, but little immune benefit after the second dose, according to new research from the Penn Institute of Immunology. The findings, published in Science Immunology, suggest only a single vaccine dose may be needed to produce a sufficient antibody response. The team found that those who did not have COVID-19—called COVID naïve—did not have a full immune response until after receiving their second vaccine dose, reinforcing the importance of completing the two recommended doses for achieving strong levels of immunity.

The study provides more insight on the underlying immunobiology of mRNA vaccines, which could help shape future vaccine strategies.

“These results are encouraging for both short- and long-term vaccine efficacy, and this adds to our understanding of the mRNA vaccine immune response through the analysis of memory B cells,” says senior author E. John Wherry, chair of the department of Systems Pharmacology and Translational Therapeutics and director of the Penn Institute of Immunology in the Perelman School of Medicine.

The human immune response to vaccines and infections result in two major outcomes—the production of antibodies that provide rapid immunity and the creation of memory B cells, which assist in long-term immunity. This study represents one of the first to uncover how memory B cell responses differ after vaccination in people who previously experienced infection, compared to those who have not had COVID-19.

“Previous COVID-19 mRNA vaccine studies on vaccinated individuals have focused on antibodies more than memory B cells. Memory B cells are a strong predictor of future antibody responses, which is why it’s vital to measure B cell responses to these vaccines,” Wherry says. “This effort to examine memory B cells is important for understanding long-term protection and the ability to respond to variants.”