While the mRNA vaccines induce strong immune responses against the virus in almost everyone, data shows those who were previously infected with the virus have even greater immune responses after vaccination compared to fully vaccinated people who never had COVID-19, according to a study by researchers from the University of Minnesota.
“Memory B cells are capable of rapid antibody production after re-infection, which is critical for immunity as antibody levels decline,” Marc Jenkins, PhD, Professor and Director of the Center for Immunology at the University of Minnesota Medical School. “Our research shows that fully vaccinated people who had a prior SARS-CoV-2 infection end up with an even larger number of memory B cells than fully vaccinated people who have not had an infection.”
The study found that:
- People with a previous SARS-CoV-2 infection had a large number of spike-specific memory B cells before vaccination, and after the first dose of an mRNA vaccine, had a significant boost in spike-specific memory B cells — but not after the second dose.
- Despite the weaker response to the second mRNA dose, people with a previous SARS-CoV-2 infection still ended up with a larger number of spike-specific memory B cells than fully vaccinated people who never had the virus.
- The spike-specific memory B cells in people with a previous SARS-CoV-2 infection bound more tightly to the spike protein of the virus compared to the memory B cells induced in uninfected people after a single mRNA vaccination.
This team is now studying memory B cell formation in fully vaccinated people with immunosuppressed systems.
