To determine neutralizing activity against the severe acute respiratory syndrome coronavirus 2 ancestral strain and 4 variants of concern, we tested serum from 30 persons with breakthrough infection after 2-dose vaccination. Cross-variant neutralizing activity was comparable to that after 3-dose vaccination. Shorter intervals between vaccination and breakthrough infection correlated with lower neutralizing titers.
Keywords: 2019 novel coronavirus disease; B cell; COVID-19; SARS-CoV-2; coronavirus disease; immunity; mRNA; neutralizing antibody; respiratory infections; severe acute respiratory syndrome coronavirus 2; vaccines; viruses; zoonoses.