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Influenza Vaccine Effectiveness in the US
Clin Infect Dis; ePub 2016 Oct 4; Zimmerman, et al
The 2014-2015 influenza vaccines were effective against influenza B in the US, but not against the predominant influenza A/H3N2 virus, a recent study found. Vaccine effectiveness (VE) across age groups and vaccine types was examined among individuals seeking outpatient treatment for acute respiratory illness from 5 US sites. Researchers found:
- Of the 9,311 participants with complete data, 7,078 (76%) were negative for influenza, 1,840 (19.8%) were positive for influenza A (A/H3N2, n=1,817) and 395 (4.2%) for influenza B (B/Yamagata, n=340).
- Overall adjusted VE for influenza A and B was 19% and was statistically significant in all age strata except aged 18 to 64 years.
- Adjusted VE for influenza B/Yamagata was 55%, but was only 6% against A/H3N2-associated illness.
- In participants aged 2 to 8 years, VE against A/H3N2 was 15% for inactivated influenza vaccine (IIV) and -3% for live attenuated influenza vaccine (LAIV); but VE against B/Yamagata was 40% for IIV and 74% for LAIV.
Citation:
Zimmerman RK, Nowalk MP, Chung J, et al. 2014-2015 influenza vaccine effectiveness in the United States by vaccine type. [Published online ahead of print October 4, 2016]. Clin Infect Dis. doi:10.1093/cid/ciw635.