Declining Prevalence of SARS-CoV-2 Antibodies among Vaccinated Nursing Home Residents and Staff Six Months after the Primary BNT162b2 Vaccination Campaign in Belgium: A Prospective Cohort Study

Abstract

In the SCOPE study, we monitored SARS-CoV-2 antibodies in a national sample of residents and staff from Belgian nursing homes. Here, we report the seroprevalence among infected and infection-naive residents and staff after the primary COVID-19 vaccination campaign. Among 1554 vaccinated nursing home residents and 1082 vaccinated staff from 69 nursing homes in Belgium, we assessed the proportion having SARS-CoV-2 antibodies approximately two (April 2021), four (June 2021), and six months (August 2021) after a two-dose regimen of the BNT162b2 vaccine. We measured the seroprevalence using SARS-CoV-2 antibody rapid tests and collected socio-demographic and COVID-19 medical data using an online questionnaire. Two months after vaccination (baseline), we found a seroprevalence of 91% (95% CI: 89–93) among vaccinated residents and 99% (95% CI: 98–99) among vaccinated staff. Six months after vaccination, the seroprevalence significantly decreased to 68% (95% CI: 64–72) among residents and to 89% (95% CI; 86–91) among staff (p < 0.001). The seroprevalence was more likely to decrease among infection-naive residents, older residents, or residents with a high care dependency level. These findings emphasize the need for close monitoring of nursing home residents, as a substantial part of this population fails to mount a persistent antibody response after BNT162b2 vaccination.

Validation of a rapid SARS-CoV-2 antibody test in general practice

“…This information can be used to guide vaccine campaigns in specific populations. This is also suggested by Meyers et al who found a faster decline in SARS-CoV-2 antibodies’ prevalence among nursing home residents 38…”

“…This is also suggested by Meyers et al who found a faster decline in SARS-CoV-2 antibodies’ prevalence among nursing home residents. 38 …”

Vaccine Hesitancy towards the COVID-19 Vaccine in a Random National Sample of Belgian Nursing Home Staff Members

“…However, the participation of a multi-disciplinary group in the elaboration of the questionnaire allowed us to assess and improve its validity before its launch [25]. Third, hesitation concerning the type of vaccine was not analysed in this study, as the majority of this population was offered the vaccine BNT162b2 (Pfizer-BioNtech) [4]. Fourth, vaccine hesitancy questions were collected after the vaccination campaign, which restricts our analysis to a very specific context and could have introduced a recall bias.…”

“…The first Belgian vaccination campaign in nursing homes took place between 28 December 2020 and 24 March 2021 [3]. Data from the first analysis of a national study on the seroprevalence of SARS-CoV-2 antibodies showed that, during the COVID-19 vaccination campaign (February-March 2021), NHS in Belgium had a lower vaccination rate for COVID-19 compared to NHR, with 48% and 68% fully vaccinated with BNT162b2 (Pfizer-BioNtech), respectively [4]. This disparity in vaccination rates between NHS and NHR has previously been observed for other vaccines, such as the influenza vaccination [5].…”

Vaccine hesitancy for the COVID-19 vaccine booster dose among nursing home staff fully vaccinated with the primary vaccination course in Belgium

“…However, the emergence of new variants and the rapid decline in vaccine-induced immunity over time, has required new vaccination campaigns for booster doses [7] . The particularly rapid decline in vaccine efficacy in NHR also led to the prioritisation of NH for the first booster dose, the campaign started in September 2021 in Belgium [6] , [8] , [9] .…”