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Influenza Vaccine Effectiveness Among Children With and Without Underlying Conditions
Haya Hayek1, Emma K Noble2,3, Laura S Stewart1
1Vanderbilt University Medical Center, Nashville, Tennessee.
Insights
Influenza vaccination is effective for children, including those with underlying health conditions. This study found vaccine effectiveness (VE) was 43% for children with underlying conditions and 53% for those without.
Area of Science:
- Pediatric infectious diseases
- Vaccinology
- Public health
Background:
- Annual influenza vaccination is recommended for children aged 6 months and older in the US.
- Children with underlying conditions face higher risks of severe influenza complications.
- Vaccine effectiveness (VE) in this high-risk group is less understood.
Purpose of the Study:
- To assess influenza vaccine effectiveness (VE) against laboratory-confirmed influenza.
- To compare VE in children with and without underlying conditions.
- To evaluate VE in children presenting to emergency departments or hospitalized.
Main Methods:
- Enrolled 15,875 US children (6 months–17 years) across 5 influenza seasons (2015-2020).
- Confirmed influenza via molecular testing; verified vaccination status through registries/clinicians.
- Abstracted underlying conditions from medical records or parental reports.
Main Results:
- Overall VE was 43% (95% CI: 35%-50%) for children with underlying conditions and 53% (95% CI: 47%-59%) for those without.
- Significant effect modification by underlying conditions (P=.04).
- Lowest VE observed in children with respiratory conditions (31%, 95% CI: 19%-42%).
Conclusions:
- Influenza vaccination offers protection to both children with and without underlying conditions.
- Improving vaccination coverage is crucial for reducing severe influenza complications.
- Early influenza treatment is essential, especially for high-risk pediatric populations.
Objective:
Children with certain underlying conditions are at higher risk for severe influenza-related complications. In the United States, annual influenza vaccination is recommended for all children aged 6 months and older, yet vaccine effectiveness (VE) in children with underlying conditions remains less understood. We assessed VE against laboratory-confirmed influenza in children with and without underlying conditions presenting to emergency departments or admitted to hospitals.
Methods:
We enrolled US children aged 6 months to 17 years at 7 pediatric medical centers within the New Vaccine Surveillance Network during 5 influenza seasons (2015-2020). Influenza status was confirmed by molecular testing and vaccination status was verified using state immunization registries or from health care clinicians. Underlying conditions were abstracted from medical records or self-reported by parents/guardians. VE was estimated by comparing the odds of vaccination among influenza-positive cases vs controls, adjusting for age, site, and calendar time.
Results:
Of the 15 875 children included, 2821 (18%) tested positive for influenza. Overall, VE against influenza-associated emergency department visits or hospitalizations was 43% (95% CI: 35%-50%) for children with underlying conditions and 53% (95% CI: 47%-59%) for those without, and there was significant effect measure modification by the presence of underlying conditions (P = .04). VE was lowest among children with respiratory conditions (31%, 95% CI: 19%-42%).
Conclusion:
Influenza vaccination provided protection in both children with and children without underlying conditions. Efforts to improve influenza vaccination coverage and to initiate early treatment for influenza, particularly in populations at increased risk for severe influenza, are essential to reducing influenza-associated complications.
