[Early effect of vaccination on the positivity rate of salivary tests performed on nursing home staff in the Walloon Region]. / Face à la COVID-19. Effet précoce de la vaccination sur le taux de positivité des tests salivaires réalisés chez le personnel des maisons de repos en Région wallonne.

In Belgium, nursing homes (NH) were disproportionately affected by the SARS-CoV-2 pandemic. The objective of this study was to compare the risk of SARS-CoV-2 infection in vaccinated and unvaccinated staff members. METHODS: This was a prospective cohort study conducted between February 1 and April 02, 2021, in 99 nursing homes (NHs) in the Walloon Region, a few weeks after the start of the vaccination campaign. A mixed-effects logistic regression analysis was performed to assess the relationship between COVID results of molecular tests on saliva samples of the NHs' staff and their vaccination status. RESULTS: Only 32 (0,1 %) of 39 267 saliva tests were positive. Logistic analysis showed that unvaccinated nursing home staff were 4 times more likely to develop COVID-19 than vaccinated staff during the study period. CONCLUSION: This study demonstrated an early decreased risk of infection in vaccinated NHs staff. Saliva tests were designed to be convenient, less expensive and non-invasive, and could be considered as an alternative to nasopharyngeal tests.

En Belgique, les maisons de repos ont été touchées de manière disproportionnée par la pandémie de SARS-CoV-2. L'objectif de cette étude était de comparer le risque d'infection par le SARS-CoV-2 chez les membres du personnel vaccinés et non vaccinés. Méthodes : Il s'agit d'une étude de cohorte prospective qui s'est déroulée entre le 1er février et le 02 avril 2021 dans 99 maisons de repos (MR) en Région wallonne, quelques semaines après le début de la campagne de vaccination. Une analyse de régression logistique à effets mixtes a été effectuée pour évaluer la relation entre les résultats COVID des tests moléculaires sur des échantillons de salive du personnel des maisons de repos et leur statut vaccinal. Résultats : Seuls 32 (0,1 %) des 39.267 tests salivaires étaient positifs. L'analyse logistique montre que le personnel des maisons de repos non vacciné était 4 fois plus susceptible de développer la COVID-19 que le personnel vacciné pendant la période d'étude. Conclusion : cette étude a mis en évidence une réduction précoce du risque d'infection chez le personnel vacciné des maisons de repos. Les tests salivaires ont été conçus pour être pratiques, moins coûteux et non invasifs, ils pourraient être considérés comme une alternative aux tests nasopharyngés.

COVID-19 Clusters in Belgian Nursing Homes: Impact of Facility Characteristics and Vaccination on Cluster Occurrence, Duration and Severity.

COVID-19 severely affected nursing home residents from March 2020 onwards in Belgium. This study aimed to model the impact of vaccination and facility characteristics on cluster occurrence, duration and severity in this setting. Possible clusters were identified between June 2020 and January 2022, based on the Belgian COVID-19 surveillance in nursing homes. Median attack rates (AR) among residents and staff, case hospitalization rates (CHR) and case fatality rates (CFR) were calculated. A negative binomial model was used to identify the association between nursing home characteristics and the number of cases, hospital admissions and deaths and the duration of the cluster. A total of 2239 clusters were detected in more than 80% of nursing homes. Most of these (62%) occurred before the start of COVID-19 vaccination (end of December 2020). After vaccination, the number of clusters, the AR among residents and staff, the CHR and the CFR dropped. Previous cluster(s) and vaccination decreased the number of cases, hospital admissions and deaths among residents. Previous cluster experience and having started vaccination were protective factors. We recommend continued implementation of targeted interventions such as vaccination, large-scale screening and immediate implementation of additional infection prevention and control measures.

Effect of COVID-19 Vaccination Campaign in Belgian Nursing Homes on COVID-19 Cases, Hospital Admissions, and Deaths among Residents.

In view of the grave situation during the first two waves of SARS-CoV-2 virus (severe acute respiratory syndrome coronavirus-2), nursing homes (NHs) were prioritised for vaccination once vaccines became available in Belgium. The aim of this study was to assess the effect of the COVID-19 (Coronavirus Disease 2019) vaccination campaign on COVID-19 cases, hospital admissions, and deaths among residents living in Belgian NHs. All 1545 Belgian NHs were invited to participate in a COVID-19 surveillance program. In Belgium, before vaccination, COVID-19 morbidity and mortality rates were driven by the situation in the NHs. Shortly after the COVID-19 vaccination campaign, and later the booster campaign, the number of hospital admissions and deaths among NH residents dropped, while clear peaks could be observed among the general population. The impact of vaccination on virus circulation was less effective than expected. However, due to the high vaccination coverage, NH residents remain well protected against hospital admission and death due to COVID-19 more than one year after being vaccinated.