Low influenza vaccine effectiveness and the effect of previous vaccination in preventing admission with A(H1N1)pdm09 or B/Victoria-Lineage in patients 60 years old or older during the 2015/2016 influenza season.

摘要: Abstract Background The 2015/2016 influenza season was characterized in Europe by the circulation of A(H1N1)pdm09 clade 6B.1 and B/Victoria-lineage viruses. components vaccines used current past two seasons Valencia region were similar but not well matched to dominant influenza-circulating strains. We estimate vaccine effectiveness (IVE) interference previous vaccination preventing admission with or this particular season. Methods Hospital Network for Study Influenza runs an active surveillance hospital-based study collect clinical virological data from consecutive admissions possibly related influenza. Combined nasopharyngeal pharyngeal swabs are analyzed reverse transcription polymerase chain reaction, hemagglutinin is sequenced a sample positive specimens. Vaccination ascertained consulting population information system. IVE using test-negative approach. Results During 2015–2016 season, we recruited 1049 eligible patients 60 years older, 187 tested adjusted 20.2%; 95% confidence interval (CI)  −21.3–47.5% −33.2%; CI, −140.1–26.1% B/Victoria-lineage. majority viruses belonged emerging subclade, defined S162N I216T mutations protein. When restricted our analysis those vaccinated year, unadjusted 84.9% (95% CI 9.9–100.0) overall, 77.9% (−32.7–100.0%) 48.8% (−219.5–100.0%) B/Yamagata-lineage admission. Conclusions Our findings indicate that low strongly correlated No effect observed. For due mismatch lack concordance between circulating