SARS-CoV-2 neutralization after mRNA vaccination and variant breakthrough infection

Vaccination and infection by viral variants are shaping population immunity to SARS-CoV-2 ¹ and breakthrough infections of vaccinated or previously infected individuals have become common as variants evade preexisting immunity. Omicron (B.1.1.529) is highly resistant to plasma neutralizing antibodies elicited by infection with prior variants and the 2-dose mRNA vaccination regimens. However, vaccination after infection or a third mRNA vaccine dose elicit high levels of neutralizing antibodies that can also neutralize omicron to a degree ^2-4 . We compared neutralizing antibody titers in 54 individuals that had received 2 or 3 doses of mRNA vaccines and had experienced breakthrough infection with SARS-CoV-2 variants.