Factors linked to protection from Omicron in vaccinated HCWs

Editor's Note

This Israeli study finds that antibody levels were associated with protection against infection with the COVID-19 Omicron variant in vaccinated healthcare workers (HCWs).

Participants included 2,310 HCWs who had received 3 or 4 doses of an mRNA COVID-19 vaccine.

The odds of infection and substantial symptomatic disease caused by the Omicron subvariant were significantly reduced for each 10-fold increase in preinfection immunoglobin G (IgG) titers and for each 2-fold increase in neutralizing antibody titers.

Infectivity was not significantly reduced with increasing IgG or neutralizing antibody titers, in contrast to the findings for the Alpha COVID-19 variant.

The findings suggest that antibody titers were linked to protection against infection with Omicron and against symptomatic disease once infected, the researchers say.