Objectives: We evaluated the antibody response to the BNT162B2 vaccine among healthcare workers (HCWs) to identify factors associated with decreased immunogenicity. Methods: This prospective cohort study included consenting HCWs who completed a questionnaire regarding background illnesses, medications, and post-vaccination allergic reactions or rash. All HCWs were tested for anti-spike antibodies (LIAISON SARS-CoV-2 S1/S2 IgG assay) 1 and 3 months after the second vaccine dose. A multivariate mixed linear model was adjusted to participants' data and fit to predict antibody levels after the second BNT162B2 vaccine dose, based on antibody levels at 1 month and the slope between 3 months and 1 month. Multivariate analyses identified factors associated with lower antibody levels. Results: In total 1506 HCWs were tested for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) antibodies. Older age was associated with lower mean antibody levels (–1.22 AU/mL, p < 0.001, 95%CI –1.43 to –1.01). In addition, male sex (–22.16 AU/mL, p < 0.001, 95%CI –27.93 to –16.39), underlying condition (–10.86 AU/mL, p 0.007, 95%CI –18.81 to –2.91) and immunosuppressive treatment (–28.57 AU/mL, p 0.002, 95%CI –46.85 to –10.29) were associated with significantly lower mean antibody levels. Allergic reactions after vaccine administration or peri-vaccination glucocorticosteroid treatment were not correlated with antibody levels. Conclusions: Most HCWs had measurable antibodies at 3 months. Risk factors for lower antibody levels were older age, male sex, underlying condition, and immunosuppressive treatment. These factors may be considered when planning booster doses during vaccine shortages.
Bibliographical noteFunding Information:
This study was performed in collaboration with the Israeli Ministry of Health. The authors would like to thank Mira Shiloah, Nelly Zaltzman Bershadsky, Rotem Cohen, Rotem Daniel, Sara Tzafrir, Marianna Sherman, Anat Reiner-Benaim, Ronit Leiba, and Deborah Hemstreet for their contributions toward the preparation of this manuscript.
© 2021 European Society of Clinical Microbiology and Infectious Diseases
- Healthcare workers
ASJC Scopus subject areas
- Microbiology (medical)
- Infectious Diseases