Durability of Antibody Response and Frequency of SARS-CoV-2 Infection 6 Months after COVID-19 Vaccination in Healthcare Workers

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.

Automated summary

Antibodies against SARS-CoV-2 decrease but remain detectable for 6 months postvaccination. The duration of neutralizing titers is shorter against Delta variant compared to the wild-type virus. Out of 227 vaccinated healthcare workers, only 2 experienced mild breakthrough infections, despite 59 individuals showing serologic evidence of SARS-CoV-2 infection.