Follow-up SARS-CoV-2 serological study of a health care worker cohort following COVID-19 booster vaccination

• Published in: BMC infectious diseases Vol. 24; no. 1; p. 436
• Main Authors: Hönning, Alexander, Tomczyk, Sara, Hermes, Julia, Grossegesse, Marica, Hofmann, Natalie, Michel, Janine, Neumann, Markus, Nitsche, Andreas, Hoppe, Berthold, Eckmanns, Tim, Schmidt-Traub, Hajo, Zappel, Kristina
• Format: Journal Article
• Language: English
• Published: England BioMed Central Ltd 24.04.2024; BioMed Central; BMC
• Subjects: Adult; Age groups; Analysis; Antibodies; Antibodies, Viral - blood; BNT162 Vaccine - administration & dosage; BNT162 Vaccine - immunology; ChAdOx1 nCoV-19 - administration & dosage; ChAdOx1 nCoV-19 - immunology; Cohort Studies; Confidence intervals; COVID-19; COVID-19 - epidemiology; COVID-19 - immunology; COVID-19 - prevention & control; COVID-19 vaccines; COVID-19 Vaccines - administration & dosage; COVID-19 Vaccines - immunology; Disease transmission; ELISA; Enzyme-linked immunosorbent assay; Enzymes; Female; Follow-Up Studies; Gender; Germany; Germany - epidemiology; Health aspects; Health care; Health care worker; Health Personnel - statistics & numerical data; Humans; IgG antibody; Immunization, Secondary; Immunoglobulin G; Immunoglobulin G - blood; Immunoglobulins; Immunology; Infection; Infections; Investigations; Kruskal-Wallis test; Laboratories; Male; Medical personnel; Middle Aged; mRNA; Pandemics; Populations; Practice; Questionnaires; RNA; SARS-CoV-2; SARS-CoV-2 - immunology; Self report; Serology; Severe acute respiratory syndrome coronavirus 2; Statistical analysis; Surveys; Systematic review; Tertiary care hospital; Vaccination; Vaccination - statistics & numerical data; Vaccine; Vaccines; Viral diseases; Germany; SARS-CoV-2; Vaccine; Tertiary care hospital; Health care worker; Germany
• ISSN: 1471-2334; 1471-2334
• DOI: 10.1186/s12879-024-09338-5

Studies have shown that Omicron breakthrough infections can occur at higher SARS-CoV-2 antibody levels compared to previous variants. Estimating the magnitude of immunological protection induced from COVID-19 vaccination and previous infection remains important due to varying local pandemic dynamics and types of vaccination programmes, particularly among at-risk populations such as health care workers (HCWs). We analysed a follow-up SARS-CoV-2 serological survey of HCWs at a tertiary COVID-19 referral hospital in Germany following the onset of the Omicron variant. The serological survey was conducted in January 2022, one year after previous surveys in 2020 and the availability of COVID-19 boosters including BNT162b2, ChAdOx1-S, and mRNA-1273. HCWs voluntarily provided blood for serology and completed a comprehensive questionnaire. SARS-CoV-2 serological analyses were performed using an Immunoglobulin G (IgG) enzyme-linked immunosorbent assay (ELISA). Antibody levels were reported according to HCW demographic and occupational characteristics, COVID-19 vaccination and SARS-CoV-2 infection history, and multivariate linear regression was used to evaluate these associations. In January 2022 (following the fourth COVID-19 wave in Germany including the onset of the Omicron variant), 1482/1517 (97.7%) HCWs tested SARS-CoV-2 seropositive, compared to 4.6% in December 2020 (second COVID-19 wave). Approximately 80% had received three COVID-19 vaccine doses and 15% reported a previous laboratory-confirmed SARS-CoV-2 infection. SARS-CoV-2 IgG geometric mean titres ranged from 335 (95% Confidence Intervals [CI]: 258-434) among those vaccinated twice and without previous infection to 2204 (95% CI: 1919-2531) among those vaccinated three times and with previous infection. Heterologous COVID-19 vaccination combinations including a mRNA-1273 booster were significantly associated with the highest IgG antibody levels compared to other schemes. There was an 8-to 10-fold increase in IgG antibody levels among 31 HCWs who reported a SARS-CoV-2 infection in May 2020 to January 2022 after COVID-19 booster vaccination. Our findings demonstrate the importance of ongoing COVID-19 booster vaccination strategies in the context of variants such as Omicron and despite hybrid immunity from previous SARS-CoV-2 infections, particularly for at-risk populations such as HCWs. Where feasible, effective types of booster vaccination, such as mRNA vaccines, and the appropriate timing of administration should be carefully considered.