The following is a summary of “Follow-up SARS-CoV-2 serological study of a health care worker cohort following COVID-19 booster vaccination,” published in the April 2024 issue of Infectious Disease by Hönning et al.

Despite vaccination and prior infection, healthcare workers continue to experience breakthrough Omicron infections, highlighting the need to understand immune protection levels against this variant.

Researchers conducted a retrospective analysis of SARS-CoV-2 antibody levels among healthcare workers in a German COVID-19 hospital after the emergence of the Omicron variant.

They conducted the serological survey in January 2022, following previous surveys in 2020 and the introduction of COVID-19 boosters like BNT162b2, ChAdOx1-S, and mRNA-1273. HCWs willingly contributed blood samples and filled out a detailed questionnaire. The study employed an Immunoglobulin G (IgG) ELISA for SARS-CoV-2 serological analyses. Antibody levels were categorized according to HCW demographics, job roles, COVID-19 vaccination status, and history of SARS-CoV-2 infection. Multivariate linear regression was used to evaluate these relationships.

The results showed that amidst the fourth COVID-19 wave in Germany (January 2022), including the emergence of the Omicron variant, 97.7% of HCWs (1482 out of 1517) tested positive for SARS-CoV-2, contrasting with 4.6% during the second wave in December 2020. About 80% had received three COVID-19 vaccine doses, with 15% reporting previous lab-confirmed SARS-CoV-2 infection. SARS-CoV-2 IgG geometric mean titers ranged from 335 (95% CI: 258–434) among those double-vaccinated without previous infection to 2204 (95% CI: 1919–2531) among those triple-vaccinated with prior infection. Heterologous COVID-19 vaccination regimens, including an mRNA-1273 booster, correlated significantly with the highest IgG antibody levels. Following COVID-19 booster vaccination, 31 HCWs who had reported a SARS-CoV-2 infection (May 2020 and January 2022) experienced an 8 to 10-fold increase in IgG antibody levels.

Investigators concluded that waning immunity from vaccination and prior infection necessitates ongoing booster programs, especially mRNA vaccines, for HCWs facing Omicron variant threats.

Source: bmcinfectdis.biomedcentral.com/articles/10.1186/s12879-024-09338-5