Delayed Antibody and T-Cell Response to BNT162b2 Vaccination in the Elderly, Germany.

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From: Emerging Infectious Diseases(Vol. 27, Issue 8)
Publisher: U.S. National Center for Infectious Diseases
Document Type: Report
Length: 2,442 words
Lexile Measure: 1440L

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We detected delayed and reduced antibody and T-cell responses after BNT162b2 vaccination in 71 elderly persons (median age 81 years) compared with 123 healthcare workers (median age 34 years) in Germany. These data emphasize that nonpharmaceutical interventions for coronavirus disease remain crucial and that additional immunizations for the elderly might become necessary.

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic has led to an urgent need for vaccines, particularly among persons at high risk for severe disease and death, such as the elderly (1). Efficacy against severe coronavirus disease (COVID-19) of mRNA vaccine BNT162b2 (Pfizer-BioNTech, https://www.pfizer.com) is reported to be >90% starting 7 days after the second vaccination; robust antibody and T-cell response has been demonstrated consistently across age groups (2-4). However, only 4.3% of participants in the BNT162b2 efficacy trial were [greater than or equal to] 75 years of age (4). Given the elderly generally have weaker immune responses after vaccination, more detailed investigation is necessary (4,5).

The Study

In a prospective observational cohort study, we investigated SARS-CoV-2-specific antibodies, maturation of IgG avidity, and interferon-Y (IFN-[gamma]) release of SARS-CoV-2-specific T cells in 2 cohorts of young and elderly BNT162b2-vaccinated persons (Table). Participants were recruited from 2 studies conducted at Charite-Universitatsmedizin Berlin, both conducted in accordance with the Declaration of Helsinki and Good Clinical Practice (https://www.ema.europa. eu/en/documents/scientific-guideline/ich-e-6-r2-guideline-good-clinical- practice-step-5_en.pdf) and approved by the local ethics committee (EA4/244/20 and EA4/245/20)

The first cohort consisted of 123 healthcare workers; median age was 34 (interquartile range [IQR] 20-64) years. The second cohort consisted of 71 elderly residents of an assisted living facility; median age was 81 (IQR 70-96) years. Blood samples were taken before the first vaccination (week 0), just before the second vaccination (week 3), and 4 weeks after the second vaccination (week 7). To discriminate between vaccine-induced antibody response and convalescent SARS-CoV-2 infection, we used the SeraSpot Anti-SARS-CoV-2 IgG microarray-based immunoassay including nucleocapsid and spike as antigens (Seramun Diagnostica GmbH, https://www.seramun.com) (Appendix, https://wwwnc.cdc.gov/EID/article/27/8/21-1145 App1.pdf). Ten of 123 healthcare workers and 1 of 71 elderly participants showed reactive anti-nucleocapsid or anti-spike IgG before the first vaccination and were excluded from further analyses.

At week 3, in the younger cohort, 93/107 (86.9%, 95% CI 79.2%-92.0%) participants showed reactive SARS-CoV-2 receptor-binding domain (RBD) IgG, compared with only 16/52 elderly participants (30.8%, 95% CI 19.9%-44.3%). At week 7, the antibody response rate had increased in both cohorts, to 112/113 in younger participants (99.1%, 95% CI 95.2%-100.0%) and 64/70 in the elderly cohort (91.4%, 95% CI 82.5%-96.0%) (Figure, panel A; Appendix Table). The comparison of SARS-CoV-2 RBD IgG levels demonstrated a significant difference in the 2 cohorts at both week 3 (p<0.0001) and week 7 (p = 0.0003) (Appendix Table), indicating a substantial delay and overall reduced antibody response in elderly participants. We observed similar kinetics and differences between cohorts for antibody responses to 2 further SARS-CoV-2 spike antigens: the S1 subdomain and the full spike protein (Appendix Table, Figure).

We further confirmed the delayed and reduced antibody response in the elderly by measurement of the...

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