Objectives: To estimate influenza vaccine effectiveness (VE) in the pediatric population (<18 years) attending primary care in the European Union and European Economic Area in 2022/2023 and 2023/2024.
Methods: General practitioners swabbed and interviewed patients with acute respiratory tract infection. We conducted a test-negative case-control study and used logistic regression to estimate VE against any influenza and specific (sub)types, overall and by age group, and within the vaccine recommendation target group.
Results: Among 10 368 children in 2022/23, 3286 (32%) tested polymerase chain reaction-positive for influenza virus; among 9270 children in 2023/24, 1567 (17%) tested positive. Influenza A(H3N2) and B predominated in 2022/23, and influenza A(H1N1)pdm09 in 2023/24. Among the test-negative controls, 17% were part of the vaccine recommendation target group in 2022/23 and 38% in 2023/24. In 2022/23, overall VE against any influenza was 68% (95% CI: 59-76); 57% (95% CI: 26-76) against influenza A(H1N1)pdm09; 54% (95% CI: 33-69) against influenza A(H3N2); 83% (95% CI: 74-90) against influenza B. In 2023/24, overall VE against any influenza was 71% (95% CI: 62-78); 75% (95% CI: 64-83) against influenza A(H1N1)pdm09; 40% (95% CI: 4-64) against influenza A(H3N2); and 92% (95% CI: 63-100) against influenza B. All VE estimates varied by age and vaccine recommendation target group.
Conclusions: In 2022/23 and 2023/24, more than two-thirds of vaccinated children were protected against primary care-attended influenza infection in Europe. Monitoring VE in children can help inform influenza immunization programs.