Adverse Events Following One Dose of mRNA COVID-19 Vaccination among U.S. Nursing Home Residents with and without a Previous SARS-CoV-2 Infection

Bardenheier, Barbara H.; Gravenstein, Stefan; Blackman, Carolyn; Gutman, Roee; Sarkar, Indra Neil; Feifer, Richard A.; White, Elizabeth M.; McConeghy, Kevin; Nanda, Aman; Bosco, Elliott; Mor, Vincent

Objectives To compare rates of adverse events following COVID-19 vaccination among nursing home residents with and without previous SARS-CoV-2 infection. Design Prospective cohort. Setting and Participants 20,918 nursing home residents who received the first dose of mRNA COVID-19 vaccine from December 18, 2020 through February 14, 2021 in 284 facilities within Genesis Healthcare, a large nursing home (NH) provider spanning 24 U.S. states. Methods We screened the electronic health record for adverse events, classified by the Brighton Collaboration, occurring within 15 days of residents’ first COVID-19 vaccine dose. All events were confirmed by physician chart review. To obtain risk ratios, multilevel logistic regression model that accounted for clustering (variability) across nursing homes was implemented. To balance the probability of prior SARS-CoV-2 infection (previous positive test or ICD-10-CM diagnosis) more than 20 days prior to vaccination, we used inverse probability weighting. To adjust for multiplicity of adverse events tested, we used a false discovery rate procedure. Results Statistically significant differences existed between those without (n=13,163) and with previous SARS-CoV-2 infection (symptomatic (n=5,617) and asymptomatic (n=2,138)) for all baseline characteristics assessed. Only one adverse event was reported among those with previous SARS-CoV-2 infection (asymptomatic), venous thromboembolism (46.8 per 100,000 residents 95%CI 8.3, 264.5) which was not significantly different from the rate reported for those without previous infection (30.4 per 100,000 95%CI: 11.8, 78.1). Several other adverse events were observed for those with no previous infection, but were not statistically significantly higher than those reported with previous infection after adjustments for multiple comparisons. Conclusions and Implications Although reactogenicity increases with pre-existing immunity, we did not find that vaccination among those with previous SARS-CoV-2 infection resulted in higher rates of adverse events than those without previous infection. This study stresses the importance of monitoring novel vaccines for adverse events of in this vulnerable population.