University of Michigan
Department of Pediatrics
Evidence-Based Pediatrics Web Site

Question

• In healthy pediatric patients, is the influenza vaccine effective in preventing influenza illness in vaccinated children compared to unvaccinated children?

Clinical Bottom Lines

1. This case-control study suggests that even in an influenza season with a suboptimal vaccine match, receipt of all recommended doses of trivalent inactivated influenza vaccine was associated with halving of laboratory-confirmed influenza-related medical visits among children 6 to 59 months of age in 1 of 2 study years.¹
2. New AAP recommendations are now that all children 6 months – 18 years receive influenza vaccination.²

Summary of Key Evidence

1. Multi-center (three distinct counties) and multi-setting (outpatient and ED/Inpatient) case-control study evaluating effectiveness of influenza vaccination against laboratory confirmed influenza during 2003-2004 and 2004-2005 influenza seasons in children 6 to 59 months of age.
2. Included: patients presenting to both inpatient (hospitalizations) or outpatient (ED and clinic) visits with acute respiratory illness or febrile illness. Nasal/throat swabs obtained: positive  case subject, negative  control subject. Then vaccination status obtained.
3. Matched for age, time frame, insurance status, presence of underlying medical condition, setting. VE calculated as (1 – aOR) x 100.
4. Receipt of all recommended doses of influenza vaccine was associated with halving of laboratory-confirmed influenza-related medical visits among children 6 to 59 months of age in 1 of 2 study years (2004-2005: VE ~60% across age groups was statistically significant).
5. This was despite suboptimal matches between vaccine and circulating influenza strains in both years.
6. Receipt of partial immunization was not protective against influenza related medical visits.

Additional Comments

• 1. Because of changes in vaccination recommendations, many more children are now recommended to receive vaccinations to protect against influenza
• 2. Influenza vaccine effectiveness has not been well characterized in young children and can vary from season to season.

Citation

1. Vaccine effectiveness against laboratory-confirmed influenza in children 6 to 59 months of age during the 2003-2004 and 2004-2005 influenza seasons. Eisenberg KW. Pediatrics, 2008 Nov;122(5):911-9.
2. Prevention of Influenza: Recommendations for Influenza Immunization of Children, 2008 Committee on Infectious Diseases Pediatrics 2008122;1135-1141; originally published online Sep 8, 2008; DOI: 10.1542/peds List references here

CAT Author: Brenden Hursh, MD

CAT Appraisers: Francis McBee Orzulak, MD

Date appraised: 12/16/08