Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) antibodies decay but persist 6 months postvaccination; lower levels of neutralizing titers persist against Delta than wild-type virus. Of 227 vaccinated healthcare workers tested, only 2 experienced outpatient symptomatic breakthrough infections, despite 59/227 exhibiting serologic evidence of SARS-CoV-2 infection, defined as presence of nucleocapsid protein antibodies.
Keywords: BNT162b2; COVID-19; SARS-CoV-2; United States; coronavirus disease; healthcare workers; respiratory infections; severe acute respiratory syndrome coronavirus 2; vaccine-preventable diseases; viruses; zoonoses.