LAUSR

Although infections among vaccinated individuals lead to milder COVID-19 symptoms relative to unvaccinated subjects, the specificity and durability of antibody responses elicited by breakthrough cases remain unknown. Here, we demonstrate that breakthrough infections induce serum binding and neutralizing antibody responses that are markedly more potent, durable and resilient to spike mutations observed in variants than those in subjects who received only two doses of vaccine. However, we show that breakthrough cases, subjects who were vaccinated after infection and individuals vaccinated three times have serum neutralizing activity of comparable magnitude and breadth, indicating that increased number of exposures to SARS-CoV-2 antigen(s) enhance the quality of antibody responses. Neutralization of SARS-CoV was moderate, however, underscoring the importance of developing vaccines eliciting broad sarbecovirus immunity for pandemic preparedness.