Concurrent administration of influenza and zoster vaccines is associated with decreased receipt of the influenza vaccine the following year, according to a study in JAMA Network Open. Benjamin N. Rome, MD, MPH, and colleagues used national claims data from patients with commercial insurance and Medicare Advantage to assess whether concurrent administration of influenza and zoster vaccines between August 2018 and March 2019 was related to a decreased likelihood of influenza vaccination the following year. Among 89,237 individuals included in the study, influenza vaccine uptake the next season (2019-2020) was lower among 27,161 individuals who received concurrent influenza and zoster vaccines versus 62,076 individuals who received the vaccines on separate days (87.3% vs 91.3%; adjusted OR, 0.74). Results were similar across subgroups. “One possible explanation is that some patients could have misattributed systemic side effects caused by the zoster vaccine to the influenza vaccine,” the authors wrote.