Comparative Analysis of Adverse Event Rates and Severity Following COVID-19 mRNA Vaccinations Among SARS-CoV-2 Naïve Nursing Home Residents and Staff

We aimed to assess the rate and severity of adverse events (AEs), and the relationship between antibody responses and AEs after COVID-19 mRNA vaccination in a nursing home cohort. Ninety-five SARS-CoV-2 naïve participants, consisting of 26 staff (median age, 51 years) and 69 residents (median age, 88 years), were evaluated for the rate and severity of local and systemic AEs. The severity of AEs was evaluated using grading scale for each sign or symptom, and expressed as the AE score. The rates of most AEs were considerably lower in the residents after the first to the fifth dose of the mRNA vaccination, compared to the staff. The severity of AEs using AE scores were also considerably lower in the residents after the first to the fifth dose of vaccination, compared to the staff. No clear relationship was detected between receptor-binding domain IgG or neutralizing titer levels and the cumulative AE score either in staff or residents after the second, third, or fifth dose of the mRNA vaccination, although there were two exceptions. Our conclusion of lower event occurrence and milder side effects strongly corroborates the science-driven proposal of COVID-19 mRNA vaccinations for older generations in high-risk care facilities.