Effects of BNT162b2 mRNA Vaccination on COVID-19 Disease, Hospitalisation and Mortality in Nursing Homes and Healthcare Workers: A Prospective Cohort Study Including 28,594 Nursing Home Residents, 26,238 Nursing Home Staff, and 61,951 Healthcare Workers in Catalonia

Background: Spain began vaccinating priority groups against COVID-19 with BNT162b2 in late December 2020. We report associations of vaccination with COVID-19 infection, hospitalisation, and mortality among nursing home residents, nursing home staff, and healthcare workers.  Methods: We analysed three cohorts of all nursing home residents, nursing home staff, and healthcare workers in Catalonia on 27 December 2020. Data were obtained from linked primary care, RT-PCR and lateral flow test, hospital, and mortality records. Those with a pre-study COVID-19 diagnosis or no linked electronic medical records were excluded. Two doses of BNT162b2 were administered 3 weeks apart. Participants were followed until the earliest of an outcome (confirmed COVID-19 infection, hospitalisation, and mortality) or 5 March 2021. Participants could contribute data to the unvaccinated, one-dose, and two-dose groups. Analyses were conducted using time-varying Cox regression. Multivariable adjustment for imbalances in socio-demographics, comorbidity, and polypharmacy.  Findings: We included 28,594 nursing home residents, 26,238 nursing home staff, and 61,951 healthcare workers, of whom 2,405, 1,584, and 2,672 received COVID-19 diagnoses; 383, 35, and 76 were hospitalised; and 409, 0, and 1 died. The adjusted hazard ratio (HR) (95% confidence interval) for COVID-19 infection after two-dose vaccination was 0·08 (0·07-0·09) for nursing home residents, 0·12 (0·10-0·15) for nursing home staff, and 0·05 (0·04-0·07) for healthcare workers. The adjusted HRs for hospitalisation and mortality after two-dose vaccination were 0·03 (0·02-0·05) and 0·02 (0·01-0·03), respectively, for nursing home residents. Nursing home staff and healthcare workers recorded insufficient events for mortality analysis. Interpretation Vaccination was associated with 85%-96% reduction in SARS-CoV-2 infection in all three cohorts, and bigger reductions in hospitalisations and mortality amongst nursing home residents for up to two months. More data are needed on the long-term effects of COVID-19 vaccines.  Funding: Partially supported by National Institute of Health Research UK, We do not have any other funding acknowledgements. Declaration of Interest: None to declare. Ethical Approval: The study was approved by the Clinical Research Ethics Committee of the IDIAP Jordi Gol with reference number 21/045-PCV.