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Multicenter Study
. 2021 Jan 27;18(3):1129.
doi: 10.3390/ijerph18031129.

Influenza Vaccine Effectiveness and Waning Effect in Hospitalized Older Adults. Valencia Region, Spain, 2018/2019 Season

Ainara Mira-Iglesias  1 , F Xavier López-Labrador  1   2 , Javier García-Rubio  1 , Beatriz Mengual-Chuliá  1 , Miguel Tortajada-Girbés  3 , Joan Mollar-Maseres  4 , Mario Carballido-Fernández  5   6 , Germán Schwarz-Chavarri  7 , Joan Puig-Barberà  1   8 , Javier Díez-Domingo  1
Affiliations
Multicenter Study

Influenza Vaccine Effectiveness and Waning Effect in Hospitalized Older Adults. Valencia Region, Spain, 2018/2019 Season

Ainara Mira-Iglesias et al. Int J Environ Res Public Health. .

Abstract

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.

Keywords: effectiveness; hospitalizations; influenza; surveillance; vaccine; waning.

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Conflict of interest statement

J.D.D. has been Principal Investigator in Clinical Trials sponsored by SPMSD, MSD, GSK, and Pfizer. J.D.D. acted as Advisor for GSK and SPMSD. Other authors declare no conflict of interest. Sanofi Pasteur had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript, or in the decision to publish the results.

Figures

Figure 1
Figure 1
Selection process and influenza status of patients ≥65 years old for the influenza vaccine effectiveness (IVE) study. Results from the Valencia Hospital Network for the Study of Influenza (VAHNSI), Spain, in the 2018/2019 influenza season.
Figure 2
Figure 2
Admissions with laboratory-confirmed influenza by epidemiological week in patients ≥65 years old. Influenza positivity percentage by epidemiological week. Valencia Hospital Network for the Study of Influenza (VAHNSI), Spain, in the 2018/2019 influenza season.
Figure 3
Figure 3
Phylogenetic analysis and mutational profiles for the A/H1N1pdm09 clades and sequenced isolates. Changes potentially gaining a glycosylation site are indicated in yellow. ML tree constructed using RAxML and the GTR-GAMMA substitution model.
Figure 4
Figure 4
Phylogenetic analysis and mutational profiles for the A/H3N2pdm09 clades and sequenced isolates. Changes potentially gaining a glycosylation site are indicated in yellow, whereas those potentially losing a glycosylation site are indicated in red. ML tree constructed using RAxML (GTR-GAMMA substitution model).
See this image and copyright information in PMC

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