- Despite 38% vaccine effectiveness (VE), influenza vaccination significantly reduced risk of any outpatient influenza-associated medically attended illness, A(H3N2) illness, and deaths during 2017-2018 season.
Why this matters
- Vaccination remains one of the most important strategies to prevent influenza, related morbidity.
- Encourage influenza vaccine uptake among all patients during routine visits.
- 2017-2018 influenza-associated events: 47.9M illnesses, 22.1M medical visits, 953,000 hospitalizations, 79,400 deaths.
- Adults aged >65 years: 15% of illnesses, 70%, 90% of hospitalizations, deaths, respectively.
- A(H3N2) associated with highest illness rates.
- 8436 U.S. Flu VE Network enrollees included: adjusted 38% (95% CI, 31%-43%) VE against influenza A or B.
- VE varied by age group; adjusted VE for A(H3N2) was 22% (95% CI, 12%-31%), for A(H1N1)pdm09 62% (95% CI, 50%-71%), influenza B 50% (95% CI, 41%-57%).
- Vaccination prevented 109,000 (95% credible intervals [Crl], 38,900-231,000) hospitalizations (10% of expected), 8000 (95% Crl, 1100-21,000) influenza-associated (9% expected) deaths overall, ~39% (95% Crl, 30%-45%) in children ages 6 months to 4 years.
- 2017-2018 influenza season surveillance report assessing VE, influenza type/subtype-specific burden, and number of influenza-associated illnesses, medical visits, hospitalizations, deaths prevented by vaccination.
- Funding: CDC.
- Multipliers do not reflect current practice.
- Subtype rate estimates imputed.
- Waning VE unaccounted for.
- Self-report bias.
- Skewed credible intervals.