For months, COVID-19 vaccine makers have been studying the potential need for booster shots down the line. Those studies have focused on if, and when, they’re needed, but recent studies also have looked at immunity levels.
Immune system memory in bone marrow suggests that those booster shots may not be needed after all.
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“We know immunity levels tend to drop off after a few months, whether you’ve had the infection or been vaccinated, but what we don’t know is how long immunity lasts,” said Dr. Thomas Huth with Reid Health.
One study, which included several researchers from Washington University in St. Louis, examined blood tests in 77 people and bone marrow in almost 20 people. The data was used to determine the potential rate of reinfection in those who tested positive for COVID-19 and the level of immunity they carried over time.
The study showed in the first few months after a patient tested positive for the virus, that antibody levels dropped off quicker, but then started to level out.
A second study from BIORXIV had similar findings. The BIORXIV study examined 63 COVID-19 patients, 41 percent of whom had received the mRNA vaccines like Pfizer or Moderna. The study found that memory B cells were about the same from 6 to 12 months after initial infections.
Memory B cells are responsible for the long-term humoral immunity elicited by most vaccines, according to the Journal of Immunology.
Huth said specifically the study done by BIORXIV could show that those who had COVID-19 and got a vaccine, could rapidly produce antibodies if your body sees the virus again.
“With this particular study, there may be no need for re-immunization unless we find variants in particular are escaping immunization,” Huth said.
Several COVID-19 variants have surfaced in the U.S., including the U.K. and Indian variants. A study from Public Health England said the Pfizer and AstraZeneca vaccines were effective against both the Indian and U.K. variant, according to a report from BBC News last week.
The studies could help answer some of the lingering questions about potential booster shots.
“There are a couple things that could happen in terms of the future of covid-19, one would be it becomes more of a seasonal thing with slight variations year to year, just like the flu,” Huth said. “The other thing is that the immunity may decline, requiring reupping immunization.”
Huth said there is a good chance that those who get a COVID-19 vaccine will need a booster shot at some point. One vaccine maker, Novavax, is already looking at a vaccine that would combine the flu and COVID-19 vaccines.