Research is shedding light on why ‘breakthrough’ Omicron infections occur in vaccinated individuals and suggests those who are both vaccinated and experienced previous infection have better protection against getting sick again.

The research shows that having both infection and vaccination with the “wild-type” virus, or the original COVID-19 variant, provides individuals with the strongest protection against all variants; those who were unvaccinated or who had not previously had the virus were more likely to have undetectable neutralization against all variants of COVID-19. Immunity provided by vaccines appears to wane over time. The research supports Omicron-specific vaccine boosters to better protect those who have not previously been infected.

“This study shows that immunity from infection, sometimes called ‘natural immunity,’ plays an important role in protection against subsequent COVID-19 infection,” says James Baker, director of the Mary H. Weiser Food Allergy Center.

Reference: “Wild-type SARS-CoV-2 neutralizing immunity decreases across variants and over time but correlates well with diagnostic testing,” Frontiers in Immunology, Volume 14-2023. DOI: 10.3389/fimmu.2023.1055429

Source: Michigan Medicine - University of Michigan