TY - JOUR T1 - Prevalence of SARS-CoV-2 antibodies among Belgian nursing home residents and staff during the primary COVID-19 vaccination campaign. JF - Eur J Gen Pract Y1 - 2022 A1 - Eline Meyers A1 - Liselore De Rop A1 - Deschepper, Ellen A1 - Els Duysburgh A1 - Tine De Burghgraeve A1 - Pauline Van Ngoc A1 - Marina Digregorio A1 - Simon Delogne A1 - Anja Coen A1 - Nele De Clercq A1 - Laëtitia Buret A1 - Coenen, Samuel A1 - An De Sutter A1 - Beatrice Scholtes A1 - Jan Y Verbakel A1 - Piet Cools A1 - Stefan Heytens AB -

BACKGROUND: Nursing home residents (NHR) and staff have been disproportionally affected by the COVID-19 pandemic and were therefore prioritised in the COVID-19 vaccination strategy. However, frail older adults, like NHR, are known to have decreased antibody responses upon vaccination targeting other viral antigens.

OBJECTIVES: As real-world data on vaccine responsiveness, we assessed the prevalence of SARS-CoV-2 antibodies among Belgian NHR and staff during the primary COVID-19 vaccination campaign.

METHODS: In total, we tested 1629 NHR and 1356 staff across 69 Belgian NHs for the presence of SARS-CoV-2 IgM/IgG antibodies using rapid tests. We collected socio-demographic and COVID-19-related medical data through questionnaires. Sampling occurred between 1 February and 24 March 2021, in a randomly sampled population that received none, one or two BNT162b2 vaccine doses.

RESULTS: We found that during the primary vaccination campaign with 59% of the study population fully vaccinated, 74% had SARS-CoV-2 antibodies. Among fully vaccinated individuals only, fewer residents tested positive for SARS-CoV-2 antibodies (77%) than staff (98%), suggesting an impaired vaccine-induced antibody response in the elderly, with lowest seroprevalences observed among infection naïve residents. COVID-19 vaccination status and previous SARS-CoV-2 infection were predictors for SARS-CoV-2 seropositivity. Alternatively, age ≥ 80 years old, the presence of comorbidities and high care dependency predicted SARS-CoV-2 seronegativity in NHR.

CONCLUSION: These findings highlight the need for further monitoring of SARS-CoV-2 immunity upon vaccination in the elderly population, as their impaired humoral responses could imply insufficient protection against COVID-19.

TRIAL REGISTRATION: This study was retrospectively registered on ClinicalTrials.gov (NCT04738695).

M3 - 10.1080/13814788.2022.2149732 ER -