RT Journal Article SR Electronic T1 Effect of influenza vaccination in patients with asthma JF Canadian Medical Association Journal JO CMAJ FD Canadian Medical Association SP E1120 OP E1128 DO 10.1503/cmaj.201757 VO 193 IS 29 A1 Iván Martínez-Baz A1 Ana Navascués A1 Itziar Casado A1 María Eugenia Portillo A1 Marcela Guevara A1 Carlos Gómez-Ibáñez A1 Cristina Burgui A1 Carmen Ezpeleta A1 Jesús Castilla YR 2021 UL http://www.cmaj.ca/content/193/29/E1120.abstract AB BACKGROUND: Although annual influenza vaccination is recommended for persons with asthma, its effectiveness in this patient population is not well described. We evaluated the effect of influenza vaccination in the current and previous seasons in preventing influenza among people with asthma.METHODS: Using population health data from the Navarre region of Spain for the 2015/16 to 2019/20 influenza seasons, we conducted a test-negative case–control study to assess the effect of influenza vaccination in the current and 5 previous seasons. From patients presenting to hospitals and primary health care centres with influenza-like illness who underwent testing for influenza, we estimated the effects of influenza vaccination among patients with asthma overall and between those presenting as inpatients or outpatients, as well as between patients with and without asthma.RESULTS: Of 1032 patients who had asthma and were tested, we confirmed that 421 had influenza and the remaining 611 were test-negative controls. We found that the average effect of influenza vaccination was 43% (adjusted odds ratio [OR] 0.57, 95% confidence interval [CI] 0.40 to 0.80) for current-season vaccination regardless of previous doses, and 38% (adjusted OR 0.62, 95% CI 0.39 to 0.96) for vaccination in previous seasons only. Effects were similar for outpatients and inpatients. Among patients with asthma and confirmed influenza, current-season vaccination did not reduce the odds of hospital admission (adjusted OR 1.05, 95% CI 0.51 to 2.18). Influenza vaccination effects were similar for patients with and without asthma.INTERPRETATION: We estimated that, on average, current or previous influenza vaccination of people with asthma prevented almost half of influenza cases. These results support recommendations that people with asthma receive influenza vaccination.