Eurosurv. Low 2018/19 vaccine effectiveness against influenza A(H3N2) among 15–64-year-olds in Europe: exploration by birth cohort

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[h=2]Low 2018/19 vaccine effectiveness against influenza A(H3N2) among 15–64-year-olds in Europe: exploration by birth cohort

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• Esther Kissling[SUP]1[/SUP], Francisco Pozo[SUP]2[/SUP], Silke Buda[SUP]3[/SUP], Ana-Maria Vilcu[SUP]4[/SUP], Alin Gherasim[SUP]5,6[/SUP], Mia Brytting[SUP]7[/SUP], Lisa Domegan[SUP]8,9[/SUP], Ver?nica G?mez[SUP]10[/SUP], Adam Meijer[SUP]11[/SUP], Mihaela Lazar[SUP]12[/SUP], Vesna Višekruna Vučina[SUP]13[/SUP], Ralf D?rrwald[SUP]14[/SUP], Sylvie van der Werf[SUP]15,16[/SUP], Amparo Larrauri[SUP]5,6[/SUP], Theresa Enkirch[SUP]7[/SUP], Joan O’Donnell[SUP]8[/SUP], Raquel Guiomar[SUP]17[/SUP], Mari?tte Hooiveld[SUP]18[/SUP], Goranka Petrović[SUP]13[/SUP], Elena Stoian[SUP]12[/SUP], Pasi Penttinen[SUP]19[/SUP], Marta Valenciano[SUP]1[/SUP], I-MOVE primary care study team[SUP]20[/SUP]

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Introduction Influenza 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).

Aim The 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.

Methods We 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.

Results Influenza 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.

Discussion The 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.

full article

https://www.eurosurveillance.org/content/10.2807/1560-7917.ES.2019.24.48.1900604#html_fulltext

 

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[h=2]Influenza imprinting in childhood and the influence on vaccine response later in life

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• Alyson A Kelvin[SUP]1,2[/SUP], Maria Zambon[SUP]3[/SUP]

First impressions are important and often long-lasting. The first influenza virus infection during childhood, termed immune imprinting, is recognised for its influence on subsequent infections and vaccinations [1,2]. The imprinting event initiates a cascade of innate and adaptive immune responses leading to an immunological memory retained over a person’s lifetime. Recent studies in Eurosurveillance report potential implications for vaccine responses. Skowronski et al. with the Canadian Sentinel Practitioner Surveillance Network (SPSN) [3] and Kissling et al. with the Influenza Monitoring Vaccine Effectiveness (I-MOVE) in Europe [4] observed evidence of an age-related cohort effect reducing vaccine protection during the 2018/19 influenza season, which they infer occured as a result of an immunological imprinting event.

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full article


https://www.eurosurveillance.org/content/10.2807/1560-7917.ES.2019.24.48.1900720#html_fulltext