- Prior season vaccine effectiveness (VE) is not associated with reduced current VE/vaccine failure in children.
Why this matters
- Per Advisory Committee on Immunization Practices (ACIP) recommendations, annual influenza vaccination is strongly recommended in children.
- 3369 children, 50% unvaccinated, 34%, 15% received inactivated influenza vaccine (IIV), live attenuated influenza vaccine (LAIV), respectively, per enrollment season.
- A(H1N1): IIV VE was 72.4% (95% CI, 56.0%-82.7%), 67.5% (95% CI, 32.1%-84.4%) among children with, without prior season vaccination, respectively; LAIV VE was not associated with (47.5% [95% CI, 11.4%-68.9%] or without (7.8% [95% CI, −101.9% to 57.9%]) prior season vaccination.
- A(H3N2): IIV VE was 38.7% (95% CI, 6.8%-59.6%), 23.2% (95% CI, −38.3% to 57.4%) for vaccinated in prior season, unvaccinated, respectively.
- LAIV VE differed by prior season vaccine status (50.3% [95% CI, 17.0%-70.2%], −82.4% [95% CI, −267.5% to 9.5%], respectively, for vaccinated, unvaccinated in 1 prior season (P<.001 vaccine type vs receipt of iiv laiv prior season respectively p=".001).</li">
- Influenza B: VE was >50% for prior LAIV, IIV vaccination history.
- Test-negative, case-control, post hoc, multiseason analysis evaluating association of prior season vaccination and VE, and influenza risk among vaccinated children ages 2-17 years by vaccine type received.
- Funding: None disclosed.
- Small sample sizes.
- Residual confounding.