- Interim reports from CDC estimate that overall influenza vaccine effectiveness (VE) is 47% against laboratory-confirmed, medically attended influenza; higher VE seen in children.
- Companion report shows influenza activity remains elevated, with A(H1N1) strain predominating nationwide; A(H3N2) predominates in Southeastern states.
Why this matters
- Vaccination remains the most effective preventive tool against influenza-related illness, complications, and deaths, but improved coverage is needed to realize full potential.
- Continue to offer/encourage vaccination to all unvaccinated patients ages >6 months as long as influenza viruses are circulating.
- 14% (465/3245) of children/adults with acute respiratory infections (ARI) tested positive for influenza (98% influenza A, 2% influenza B).
- 74% (293), 26% (101) of 394 subtyped influenza A viruses were A(H1N1)pdm09, A(H3N2), respectively.
- Overall, 43% (198), 57% (1591) vaccinated persons were influenza-positive, -negative, respectively.
- Adjusted VE against all medically attended influenza virus-associated ARI: 47% (95% CI, 34%-57%).
- Adjusted VE for children, ages 6 months to 17 years: 61% (95% CI, 44%-73%).
- Interim US Flu VE Network surveillance report evaluating VE against laboratory-confirmed influenza associated with medically attended ARI, November 23, 2018-February 2, 2019.
- Funding: CDC.
- Small sample size.
- Self-report bias; end-of-season VE may differ.
- Data limited to outpatient medical visits vs severe complications/hospitalizations.