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. 2023 Apr 1;151(4):e2022059922.
doi: 10.1542/peds.2022-059922.

Influenza Vaccine Effectiveness Among Children: 2011-2020

Nicole Hood  1 , Brendan Flannery  1 , Manjusha Gaglani  2   3 , Madhava Beeram  2   3 , Karen Wernli  4 , Michael L Jackson  4 , Emily T Martin  5 , Arnold S Monto  5 , Richard Zimmerman  6 , Jonathan Raviotta  6 , Edward A Belongia  7 , Huong Q McLean  7 , Sara Kim  1 , Manish M Patel  1 , Jessie R Chung  1
Affiliations

Influenza Vaccine Effectiveness Among Children: 2011-2020

Nicole Hood et al. Pediatrics. .

Abstract

Background and objectives: Infants and children are at increased risk of severe influenza virus infection and its complications. Influenza vaccine effectiveness (VE) varies by age, influenza season, and influenza virus type/subtype. This study's objective was to examine the effectiveness of inactivated influenza vaccine against outpatient influenza illness in the pediatric population over 9 influenza seasons after the 2009 A(H1N1) pandemic.

Methods: During the 2011-2012 through the 2019-2020 influenza seasons at outpatient clinics at 5 sites of the US Influenza Vaccine Effectiveness Network, children aged 6 months to 17 years with an acute respiratory illness were tested for influenza using real-time, reverse-transcriptase polymerase chain reaction. Vaccine effectiveness was estimated using a test-negative design.

Results: Among 24 148 enrolled children, 28% overall tested positive for influenza, 3017 tested positive for influenza A(H3N2), 1459 for influenza A(H1N1)pdm09, and 2178 for influenza B. Among all enrollees, 39% overall were vaccinated, with 29% of influenza cases and 43% of influenza-negative controls vaccinated. Across all influenza seasons, the pooled VE for any influenza was 46% (95% confidence interval, 43-50). Overall and by type/subtype, VE against influenza illness was highest among children in the 6- to 59-month age group compared with older pediatric age groups. VE was lowest for influenza A(H3N2) virus infection.

Conclusions: Analysis of multiple seasons suggested substantial benefit against outpatient illness. Investigation of host-specific or virus-related mechanisms that may result in differences by age and virus type/subtype may help further efforts to promote increased vaccination coverage and other influenza-related preventative measures.

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Conflict of interest statement

CONFLICT OF INTEREST DISCLOSURES: Dr Monto reports research grant support from Sanofi Pasteur and personal/consulting fees from Novartis, Novavax, Protein Sciences, Seqirus, and GSK. Dr Zimmerman has research grant support from Sanofi Pasteur. Dr Gaglani reports research support from Medimmune, Novartis, Sanofi Pasteur, Pfizer, and GSK and consulting fees from BioCryst. Dr Martin reports research grant support from Merck and research funds from Roche Pharmaceuticals and personal fees from Pfizer. Dr Belongia reports research grant support from Medimmune and Seqirus. Dr McLean reports research grant support from Medimmune and Seqirus. Dr Raviotta reports research grant support from Pfizer. Dr Jackson reports research grant support from Sanofi Pasteur. All other authors report no potential conflicts.

Figures

FIGURE 1
FIGURE 1
Effectiveness of pediatric influenza vaccination against laboratory-confirmed influenza, stratified by age group, US Flu VE Network, influenza seasons 2011 - 2012 through 2019 - 2020. Vaccine effectiveness was calculated as (1 – adjusted odds ratio) × 100, in which the odds ratio is the odds of pediatric vaccination among children with influenza versus controls. Will not add to total for influenza A(H3N2) and A(H1N1)pdm09 because some influenza A virus specimens were not able to be subtyped.
FIGURE 2
FIGURE 2
Effectiveness of pediatric influenza vaccination against influenza A(H3N2), stratified by pediatric age group, antigenic match between vaccine and circulating A(H3N2) virus, and season. Seasons depicted here are those in which influenza A(H3N2) circulated predominantly.
See this image and copyright information in PMC

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