Influenza vaccine efficacy in young children attending childcare: A randomised controlled trial.
OBJECTIVE
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.
National Centre for Immunisation Research and Surveillance, The Children's Hospital at Westmead, Sydney, New South Wales, Australia.|Sydney Medical School, The University of Sydney, Sydney, New South Wales, Australia.
Jean P
JP
Li-Kim-Moy
National Centre for Immunisation Research and Surveillance, The Children's Hospital at Westmead, Sydney, New South Wales, Australia.|Sydney Medical School, The University of Sydney, Sydney, New South Wales, Australia.
Jiehui K
JK
Yin
National Centre for Immunisation Research and Surveillance, The Children's Hospital at Westmead, Sydney, New South Wales, Australia.|Sydney Medical School, The University of Sydney, Sydney, New South Wales, Australia.
Leon
L
Heron
School of Public Health, The University of Sydney, Sydney, New South Wales, Australia.
Julie
J
Leask
UQ Child Health Research Centre, The University of Queensland, Brisbane, Queensland, Australia.|Queensland Paediatric Infectious Diseases Laboratory, Queensland Children's Medical Research Institute, Children's Health Queensland, Brisbane, Queensland, Australia.
Stephen B
SB
Lambert
Queensland Paediatric Infectious Diseases Laboratory, Queensland Children's Medical Research Institute, Children's Health Queensland, Brisbane, Queensland, Australia.|Lady Cilento Children's Hospital, The University of Queensland, Brisbane, Queensland, Australia.|Department of Health, The University of Queensland, Brisbane, Queensland, Australia.
Michael
M
Nissen
UQ Child Health Research Centre, The University of Queensland, Brisbane, Queensland, Australia.|Queensland Paediatric Infectious Diseases Laboratory, Queensland Children's Medical Research Institute, Children's Health Queensland, Brisbane, Queensland, Australia.
Theo
T
Sloots
National Centre for Immunisation Research and Surveillance, The Children's Hospital at Westmead, Sydney, New South Wales, Australia.|Sydney Medical School, The University of Sydney, Sydney, New South Wales, Australia.|Department of Microbiology and Infectious Diseases, The Children's Hospital at Westmead, Sydney, New South Wales, Australia.|Marie Bashir Institute for Infectious Diseases and Biosecurity, The University of Sydney, Sydney, New South Wales, Australia.
Robert
R
Booy
D000328:Adult; D002654:Child Care; D002675:Child, Preschool; D004311:Double-Blind Method; D005260:Female; D006506:Hepatitis A / Q000517:prevention & control; D022362:Hepatitis A Vaccines / Q000008:administration & dosage; D006801:Humans; D007223:Infant; D007252:Influenza Vaccines / Q000008:administration & dosage / Q000592:standards*; D007251:Influenza, Human / Q000517:prevention & control*; D008297:Male; D008875:Middle Aged; D012042:Registries; D016896:Treatment Outcome; D015164:Vaccines, Inactivated
D022362:Hepatitis A Vaccines; D007252:Influenza Vaccines; D015164:Vaccines, Inactivated
childcare; children; influenza; randomised controlled trial; vaccination