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Influenza vaccine efficacy in young children attending childcare: A randomised controlled trial
Jean P Li-Kim-Moy1,2, Jiehui K Yin1,2, Leon Heron1,2
1National Centre for Immunisation Research and Surveillance, The Children's Hospital at Westmead, Sydney, New South Wales, Australia.
Insights
Trivalent influenza vaccine (TIV) showed 87% efficacy in young children, particularly those aged 24-48 months. The vaccine was safe, with mild side effects, suggesting value in childcare settings.
Area of Science:
- Pediatric Infectious Diseases
- Vaccinology
- Public Health
Background:
- Influenza poses a significant health burden on young children.
- Limited vaccine efficacy (VE) data exists for this demographic.
- Childcare settings are key environments for influenza transmission.
Purpose of the Study:
- To evaluate the efficacy and safety of trivalent influenza vaccine (TIV) in young children attending childcare.
- To assess VE against confirmed influenza in children aged 6 to <48 months.
Main Methods:
- A double-blind, randomized controlled trial was conducted in Sydney childcare centers (2011).
- Participants (6 to <48 months) received two doses of TIV or a control hepatitis A vaccine.
- Efficacy was determined by PCR-confirmed influenza; safety was monitored for 6 months.
Main Results:
- The influenza attack rate was 1.8% in the TIV group versus 13.4% in the control group, yielding an overall VE of 87%.
- In children aged 24 to <48 months, VE was 100% (95% CI: 16-100%), with 0 infections in the TIV group versus 8 in the control group.
- No significant safety concerns were identified, with mostly mild adverse events, except for increased mild diarrhea in TIV recipients after the second dose.
Conclusions:
- TIV demonstrated efficacy in children aged 24 to <48 months, though small sample size warrants caution.
- The vaccine was well-tolerated with no serious adverse events reported.
- Influenza vaccination in childcare settings appears valuable, supporting the need for larger confirmatory studies.
Aim:
Influenza causes a substantial burden in young children. Vaccine efficacy (VE) data are limited in this age group. We examined trivalent influenza vaccine (TIV) efficacy and safety in young children attending childcare.
Methods:
A double-blind, randomised controlled trial in children aged 6 to <48 months was conducted with recruitment from Sydney childcare centres in 2011. Children were randomised to receive two doses of TIV or control hepatitis A vaccine. Efficacy was evaluated against polymerase chain reaction-confirmed influenza using parent-collected nose/throat swabs during influenza-like-illness. Safety outcomes were assessed during 6 months of follow-up.
Results:
Fifty-seven children were allocated to influenza vaccine and 67 to control; all completed the study. The influenza attack rate was 1.8 vs 13.4% in the TIV and control groups, respectively; VE 87% (95%CI: 0-98%). For children aged 24 to <48 months, 0 vs 8 (18.6%) influenza infections occurred in the TIV and control groups respectively, giving a VE of 100% (16-100%). Efficacy was not shown in children 6 to <24 months, probably due to insufficient power. Injection site and systemic adverse events were mostly mild to moderate with no significant differences, apart from more mild diarrhoea following dose 2 in TIV recipients (11.8 vs 0%).
Conclusions:
Influenza vaccine appeared efficacious in the subgroup of children aged 24 to <48 months, although caution is required due to the small number of participants. There were no serious adverse events and most parents would vaccinate again. Influenza vaccination in a childcare setting could be valuable and a larger confirmatory study would be helpful.
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