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Effectiveness of seasonal influenza vaccines in children -- a systematic review and meta-analysis
Ivana Lukšić1, Sarah Clay, Rachel Falconer
1Ivana Luksic, Institute of Public Health, Dr Andrija Štampar, Department of Microbiology, Mirogojska 16, 10000 Zagreb, Croatia. ivana.luksic@stampar.hr
Insights
Seasonal influenza vaccines demonstrate high efficacy in children, especially live-attenuated vaccines. However, their real-world effectiveness is lower, with limited data on hospitalization rates.
Area of Science:
- Pediatric Infectious Diseases
- Vaccinology
- Public Health
Background:
- Seasonal influenza poses a significant health risk to children.
- Vaccination is a primary strategy for influenza prevention.
- Assessing vaccine performance in pediatric populations is crucial for public health policy.
Purpose of the Study:
- To evaluate the efficacy and effectiveness of seasonal influenza vaccines.
- To analyze vaccine performance in healthy children up to 18 years of age.
- To synthesize evidence from diverse study designs on influenza vaccine outcomes.
Main Methods:
- Comprehensive literature search across multiple databases (MedLine, EMBASE, etc.).
- Inclusion of randomized controlled trials, cohort, and case-control studies.
- Seven meta-analyses conducted to assess vaccine efficacy and effectiveness against influenza-like illness and laboratory-confirmed influenza.
Main Results:
- Live influenza vaccines showed high efficacy (76.4%-83.4%) against influenza.
- Inactivated influenza vaccines demonstrated lower efficacy (67.3%).
- Vaccine effectiveness against influenza-like illness was moderate for both live (31.4%-44.3%) and inactivated (32.5%-42.6%) vaccines.
Conclusions:
- Influenza vaccines exhibit high efficacy in children, with live vaccines performing particularly well.
- Observed vaccine effectiveness is lower than efficacy, indicating a gap in real-world protection.
- Further research is needed, especially regarding the impact of influenza vaccination on hospitalizations in children.
Aim:
To assess the efficacy and effectiveness of seasonal influenza vaccines in healthy children up to the age of 18 years.
Methods:
MedLine, EMBASE, CENTRAL, CINAHL, WHOLIS, LILACS, and Global Health were searched for randomized controlled trials and cohort and case-control studies investigating the efficacy or effectiveness of influenza vaccines in healthy children up to the age of 18 years. The studies were assessed for their quality and data on the outcomes of influenza-like illness, laboratory-confirmed influenza, and hospitalizations were extracted. Seven meta-analyses were performed for different vaccines and different study outcomes.
Results:
Vaccine efficacy for live vaccines, using random effects model, was as follows: (i) for similar antigen, using per-protocol analysis: 83.4% (78.3%-88.8%); (ii) for similar antigen, using intention to treat analysis: 82.5 (76.7%-88.6%); (iii) for any antigen, using per protocol analysis: 76.4% (68.7%-85.0%); (iv) for any antigen, using intention to treat analysis: 76.7% (68.8%-85.6%). Vaccine efficacy for inactivated vaccines, for similar antigen, using random effects model, was 67.3% (58.2%-77.9%). Vaccine effectiveness against influenza-like illness for live vaccines, using random effects model, was 31.4% (24.8%-39.6%) and using fixed-effect model 44.3% (42.6%-45.9%). Vaccine effectiveness against influenza-like illness for inactivated vaccines, using random effects model, was 32.5% (20.0%-52.9%) and using fixed-effect model 42.6% (38.3%-47.5%).
Conclusions:
Influenza vaccines showed high efficacy in children, particularly live vaccines. Effectiveness was lower and the data on hospitalizations were very limited.
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