Pediatrics
May 2014, VOLUME 133 / ISSUE 5
http://pediatrics.aappublications.org/current.shtml
Article
Effectiveness of Trivalent Flu Vaccine in Healthy Young Children
Christopher C. Blyth, MBBSa,b,c,d, Peter Jacoby, MScc, Paul V. Effler, MD, MPHe, Heath Kelly, MPHf,g, David W. Smith, MBBSd,h, Christine Robinsc, Gabriela A. Willis, MBBSc, Avram Levy, PhDd, Anthony D. Keil, MBBSd, and Peter C. Richmond, MBBSa,b,c
on behalf of the WAIVE Study Team
Author Affiliations
aSchool of Paediatrics and Child Health and
hSchool of Pathology and Laboratory Medicine, University of Western Australia, Perth, Australia;
bPrincess Margaret Hospital for Children, Perth, Australia;
cTelethon Institute of Child Health Research, West Perth, Australia;
dPathWest Laboratory Medicine, Nedlands, Australia;
eCommunicable Disease Control Directorate, Department of Health, Perth, Australia;
fVictorian Infectious Diseases Reference Laboratory, Melbourne, Australia; and
gAustralian National University, Australian Capital Territory, Australia
Abstract
BACKGROUND: There are few studies evaluating the effectiveness of trivalent influenza vaccination (TIV) in young children, particularly in children <2 years. The Western Australian Influenza Vaccine Effectiveness Study commenced in 2008 to evaluate a program providing TIV to children aged 6 to 59 months.
METHODS: An observational study enrolling children with influenza-like illness presenting to a tertiary pediatric hospital was conducted (2008–2012). Vaccination status was determined by parental questionnaire and confirmed via the national immunization register and/or vaccine providers. Respiratory virus polymerase chain reaction and culture were performed on nasopharyngeal samples. The test-negative design was used to estimate vaccine effectiveness (VE) by using 2 control groups: all influenza test-negative subjects and other-virus-detected (OVD) subjects. Adjusted odds ratios were estimated from models with season, month of disease onset, age, gender, indigenous status, prematurity, and comorbidities as covariates. Subjects enrolled in 2009 were excluded from VE calculations.
RESULTS: Of 2001 children enrolled, influenza was identified in 389 (20.4%) children. Another respiratory virus was identified in 1134 (59.6%) children. Overall, 295 of 1903 (15.5%) children were fully vaccinated and 161 of 1903 (8.4%) children were partially vaccinated. Vaccine uptake was significantly lower in 2010–2012 after increased febrile adverse events observed in 2010. Using test-negative controls, VE was 64.7% (95% confidence interval [CI]: 33.7%–81.2%). No difference in VE was observed with OVD controls (65.8%; 95% CI: 32.1%–82.8%). The VE for children <2 years was 85.8% (95% CI: 37.9%–96.7%).
CONCLUSIONS: This study reveals the effectiveness of TIV in young children over 4 seasons by using test-negative and OVD controls. TIV was effective in children aged <2 years. Despite demonstrated vaccine effectiveness, uptake of TIV remains suboptimal.