PHILADELPHIA, Pa. — If you’ve already recovered from a COVID-19 infection, you may not need a second vaccine dose. Researchers at Penn State say those surviving a COVID-19 infection show a “robust antibody response” to their first vaccine shot. However, their study finds “little immune benefits” upon completion of a second dose. In other words, coronavirus patients may not need that booster shot one month later.
For those you have avoided COVID, study authors say their work emphasizes how important it is to receive two full vaccine doses. The study finds these individuals only showed a full immune response after their second shot.
“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 study author E. John Wherry, PhD, chair of the department of Systems Pharmacology and Translational Therapeutics and director of the Penn Institute of Immunology, in a university release.
How does the immune system response to vaccines?
Whenever the human immune system encounters a new infection or vaccination, two things happen. The first is the production of relevant antibodies providing immediate immunity and the second is the creation of memory B cells, which help with more long-term immunity. This research is among the first ever to show memory B cell responses vary post-vaccination depending on whether or not the individual had COVID at an earlier date.
“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 explains. “This effort to examine memory B cells is important for understanding long-term protection and the ability to respond to variants.”
Researchers examined 44 healthy individuals at the time of their BioNTech/Pfizer or Moderna mRNA COVID-19 vaccination. Among that group, 11 had already recovered from a COVID infection. The team collected blood samples for “deep immune analyses” both before and after their vaccinations.
Those analyses make a compelling case that those who have already recovered from the virus only need one vaccine dose. Study authors add a single dose in this case “may be enough to induce a maximal immune response, based on both strong antibody and memory B cell responses.”
Side-effects to vaccines may actually be a good thing?
Notably, similar research conducted specifically on the D614G mutation and the B.1.351 South African variant of COVID produced similar findings.
“This is important for us to keep in mind as we consider vaccination strategies in the future and potential viral variants,” Wherry explains. “We need to make sure people have the strongest memory B cell responses available. If circulating antibodies wane over time, our data suggests that durable memory B cells could provide a rapid source of protection against re-exposure to COVID-19, including variants.”
Penn State researchers also conducted investigations into the side-effects of vaccination. While this work only involved people who had never been infected, researchers say experiencing side-effects after vaccination (fever, chills, headache) may actually signal a stronger immune response. Subjects who reported such side-effects also displayed stronger post-vaccination serum antibodies, but not memory B cells.
“Everyone has good responses to the vaccines. They work to protect people against COVID-19. But for those who may be worried about side effects, they are not necessarily a bad thing–they may actually be an indicator of an even better immune response,” Wherry concludes.
The study appears in the journal Science Immunology.