Open AccessInfluenza Vaccine Effectiveness and Waning Effect in Hospitalized Older Adults. Valencia Region, Spain, 2018/2019 Season
Author(s) -
Ainara MiraIglesias,
F. Xavier LópezLabrador,
Javier GarcíaRubio,
Beatriz MengualChuliá,
Miguel TortajadaGirbés,
Joan Mollar-Maseres,
Mario CarballidoFernández,
Germán SchwarzChavarri,
Joan Puig-Barberà,
Javier DíezDomingo
Publication year - 2021
Publication title -
international journal of environmental research and public health/international journal of environmental research and public health
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.747
H-Index - 113
eISSN - 1661-7827
pISSN - 1660-4601
DOI - 10.3390/ijerph18031129
Subject(s) - medicine , vaccination , confidence interval , influenza vaccine , confounding , seasonal influenza , pediatrics , covid-19 , immunology , disease , infectious disease (medical specialty)
Influenza vaccination is annually recommended for specific populations at risk, such as older adults. We estimated the 2018/2019 influenza vaccine effectiveness (IVE) overall, by influenza subtype, type of vaccine, and by time elapsed since vaccination among subjects 65 years old or over in a multicenter prospective study in the Valencia Hospital Surveillance Network for the Study of Influenza and other Respiratory Viruses (VAHNSI, Spain). Information about potential confounders was obtained from clinical registries and/or by interviewing patients and vaccination details were only ascertained by registries. A test-negative design was performed in order to estimate IVE. As a result, IVE was estimated at 46% (95% confidence interval (CI): (16%, 66%)), 41% (95% CI: (-34%, 74%)), and 45% (95% CI: (7%, 67%)) against overall influenza, A(H1N1)pdm09 and A(H3N2), respectively. An intra-seasonal not relevant waning effect was detected. The IVE for the adjuvanted vaccine in ≥75 years old was 45% (2%, 69%) and for the non-adjuvanted vaccine in 65-74 years old was 59% (-16%, 86%). Thus, our data revealed moderate vaccine effectiveness against influenza A(H3N2) and not significant against A(H1N1)pdm09. Significant protection was conferred by the adjuvanted vaccine to patients ≥75 years old. Moreover, an intra-seasonal not relevant waning effect was detected, and a not significant IVE decreasing trend was observed over time.