Reviewed by Tyler Stephen, MD, University of Rochester Medicine
This retrospective cohort study by Silva et al., conducted as a target trial emulation, examines whether the proportion of nursing home residents who receive influenza prophylaxis affects hospitalization or mortality. Over 35,000 nursing home resident trial observations were included after identification of an influenza outbreak (two cases within 72 hours) in nursing homes with at least 30 residents. Outcomes were compared based on whether the nursing home administered intensive chemoprophylaxis, defined as oseltamivir at any dose to 70% or more of the nursing home residents within 2 days of the outbreak identification. Residents who were in a nursing home that administered intensive chemoprophylaxis were less likely to be hospitalized at 14 days (risk ratio of 0.96). All-cause death at 14 days and all-cause hospitalization at 30 days were also lower in the intensive chemoprophylaxis group, though the confidence intervals for the risk ratio overlapped 1; similarly, all-cause death at 30 days was mildly higher, but the risk ratio overlapped 1.
While the study is limited by data heterogeneity and the risk of confounding, the authors attempted to address these issues by using inverse probability of censoring weights and clone-censor weights. Overall, however, this is a massive study that demonstrates a benefit of intensive oseltamivir prophylaxis in preventing hospitalizations within 2 weeks of influenza outbreaks in the nursing home setting. This effect may be less pronounced the further one looks from the outbreak, when baseline factors may predominate. This benefit was also seen in sensitivity analyses if the proportion of residents receiving prophylaxis was set at 60% or 80%. Overall, this is some of the strongest support for the use of chemoprophylaxis in nursing homes.
Reference:
Silva JBB, Hsieh HT, Howe CJ, Gravenstein S, Reich LA, Zullo AR. Prompt and Intensive Antiviral Chemoprophylaxis in Nursing Home Influenza Outbreaks. JAMA Intern Med. Published online March 30, 2026. doi:10.1001/jamainternmed.2026.0401
