Influenza Disease Burden and Vaccine Effectiveness in Children and Adolescents With Solid Organ Transplant: 2018-2024

Solid organ transplant (SOT) recipients have an increased risk of influenza infection. Annual vaccination is the primary strategy to reduce the burden of influenza disease, but vaccine effectiveness (VE) varies annually for influenza. There is limited data published demonstrating influenza VE in pediatric SOT over time.

We conducted a retrospective, case-control study using a test-negative design to estimate influenza VE against laboratory-confirmed influenza infections among pediatric SOT recipients aged 6 months to 21 years at two large pediatric transplant centers, spanning the six influenza seasons from fall 2018 through spring 2024. Logistic regression models were used to compare odds ratios (ORs) of vaccination in cases to controls. VE was calculated as [100% × (1 - adjusted OR)], and 95% confidence intervals (CIs) were computed around the estimates.

Across all 6 seasons, there were 4 585 patient encounters, of which 961 had an influenza test and were included in the study. Overall, 750 (78.0%) patients received the seasonal influenza vaccine, and 94 (9.9%) tested positive for influenza. Among vaccinated patients, the prevalence of influenza diagnosis was lower (6.8%) than among unvaccinated patients (20.4%) (OR 0.28, 95% CI 0.18-0.43). The adjusted VE against laboratory-confirmed influenza infection was 72.0% (95% CI 57.0-82.0) and varied by season. VE was similar between organ groups: Kidney (65.9%, 95% CI 29.7-83.4), heart (86.4%, 95% CI 59.0-95.5), and liver (71.7%, 95% CI 41.6-86.3).

Influenza vaccination decreased the risk of influenza infection among pediatric SOT recipients for the 2018-2024 influenza seasons.