title: Interim Estimates of 2016-17 Seasonal Influenza Vaccine Effectiveness - United States, February 2017.
abstract: In the United States, annual vaccination against seasonal influenza is recommended for all persons aged ≥6 months (1). Each influenza season since 2004-05, CDC has estimated the effectiveness of seasonal influenza vaccine to prevent influenza-associated, medically attended, acute respiratory illness (ARI). This report uses data, as of February 4, 2017, from 3,144 children and adults enrolled in the U.S. Influenza Vaccine Effectiveness Network (U.S. Flu VE Network) during November 28, 2016-February 4, 2017, to estimate an interim adjusted effectiveness of seasonal influenza vaccine for preventing laboratory-confirmed influenza virus infection associated with medically attended ARI. During this period, overall vaccine effectiveness (VE) (adjusted for study site, age group, sex, race/ethnicity, self-rated general health, and days from illness onset to enrollment) against influenza A and influenza B virus infection associated with medically attended ARI was 48% (95% confidence interval [CI] = 37%-57%). Most influenza infections were caused by A (H3N2) viruses. VE was estimated to be 43% (CI = 29%-54%) against illness caused by influenza A (H3N2) virus and 73% (CI = 54%-84%) against influenza B virus. These interim VE estimates indicate that influenza vaccination reduced the risk for outpatient medical visits by almost half. Because influenza activity remains elevated (2), CDC and the Advisory Committee on Immunization Practices recommend that annual influenza vaccination efforts continue as long as influenza viruses are circulating (1). Vaccination with 2016-17 influenza vaccines will reduce the number of infections with most currently circulating influenza viruses. Persons aged ≥6 months who have not yet been vaccinated this season should be vaccinated as soon as possible.
authors.forename: Brendan
authors.initials: B
authors.lastname: Flannery
authors.forename: Jessie R
authors.initials: JR
authors.lastname: Chung
authors.forename: Swathi N
authors.initials: SN
authors.lastname: Thaker
authors.forename: Arnold S
authors.initials: AS
authors.lastname: Monto
authors.forename: Emily T
authors.initials: ET
authors.lastname: Martin
authors.forename: Edward A
authors.initials: EA
authors.lastname: Belongia
authors.forename: Huong Q
authors.initials: HQ
authors.lastname: McLean
authors.forename: Manjusha
authors.initials: M
authors.lastname: Gaglani
authors.forename: Kempapura
authors.initials: K
authors.lastname: Murthy
authors.forename: Richard K
authors.initials: RK
authors.lastname: Zimmerman
authors.forename: Mary Patricia
authors.initials: MP
authors.lastname: Nowalk
authors.forename: Michael L
authors.initials: ML
authors.lastname: Jackson
authors.forename: Lisa A
authors.initials: LA
authors.lastname: Jackson
authors.forename: Angie
authors.initials: A
authors.lastname: Foust
authors.forename: Wendy
authors.initials: W
authors.lastname: Sessions
authors.forename: LaShondra
authors.initials: L
authors.lastname: Berman
authors.forename: Sarah
authors.initials: S
authors.lastname: Spencer
authors.forename: Alicia M
authors.initials: AM
authors.lastname: Fry
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D007223:Infant; D053118:Influenza A Virus, H1N1 Subtype / Q000302:isolation & purification*; D053122:Influenza A Virus, H3N2 Subtype / Q000302:isolation & purification*; D009981:Influenza B virus / Q000302:isolation & purification*; D007252:Influenza Vaccines / Q000008:administration & dosage* / Q000276:immunology; D007251:Influenza, Human / Q000453:epidemiology / Q000517:prevention & control* / Q000821:virology; D008297:Male; D008875:Middle Aged; D011159:Population Surveillance; D012621:Seasons; D014481:United States / Q000453:epidemiology; D055815:Young Adult
chemical_list: D007252:Influenza Vaccines