Please use this identifier to cite or link to this item:http://hdl.handle.net/20.500.12105/8975
Low 2018/19 vaccine effectiveness against influenza A(H3N2) among 15-64-year-olds in Europe: exploration by birth cohort
Kissling, Esther | Pozo Sanchez, Francisco ISCIII | Buda, Silke | Vilcu, Ana-Maria | Gherasim, Alin Manuel ISCIII | Brytting, Mia | Domegan, Lisa | Gómez, Verónica | Meijer, Adam | Lazar, Mihaela | Vučina, Vesna Višekruna | Dürrwald, Ralf | van der Werf, Sylvie | Larrauri, Amparo ISCIII | Enkirch, Theresa | O'Donnell, Joan | Guiomar, Raquel | Hooiveld, Mariëtte | Petrović, Goranka | Stoian, Elena | Penttinen, Pasi | Valenciano, Marta | I-Move Primary Care Study Team | Mazagatos, Clara ISCIII | Casas Flecha, Inmaculada ISCIII
Euro Surveill. 2019 Nov;24(48):1900604.
IntroductionInfluenza A(H3N2) clades 3C.2a and 3C.3a co-circulated in Europe in 2018/19. Immunological imprinting by first childhood influenza infection may induce future birth cohort differences in vaccine effectiveness (VE).AimThe I-MOVE multicentre primary care test-negative study assessed 2018/19 influenza A(H3N2) VE by age and genetic subgroups to explore VE by birth cohort.MethodsWe measured VE against influenza A(H3N2) and (sub)clades. We stratified VE by usual age groups (0-14, 15-64, ≥ 65-years). To assess the imprint-regulated effect of vaccine (I-REV) hypothesis, we further stratified the middle-aged group, notably including 32-54-year-olds (1964-86) sharing potential childhood imprinting to serine at haemagglutinin position 159.ResultsInfluenza A(H3N2) VE among all ages was -1% (95% confidence interval (CI): -24 to 18) and 46% (95% CI: 8-68), -26% (95% CI: -66 to 4) and 20% (95% CI: -20 to 46) among 0-14, 15-64 and ≥ 65-year-olds, respectively. Among 15-64-year-olds, VE against clades 3C.2a1b and 3C.3a was 15% (95% CI: -34 to 50) and -74% (95% CI: -259 to 16), respectively. VE was -18% (95% CI: -140 to 41), -53% (95% CI: -131 to -2) and -12% (95% CI: -74 to 28) among 15-31-year-olds (1987-2003), 32-54-year-olds (1964-86) and 55-64-year-olds (1954-63), respectively.DiscussionThe lowest 2018/19 influenza A(H3N2) VE was against clade 3C.3a and among those born 1964-86, corresponding to the I-REV hypothesis. The low influenza A(H3N2) VE in 15-64-year-olds and the public health impact of the I-REV hypothesis warrant further study.
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