Effects of Influenza Vaccination in the United States During the 2017-2018 Influenza Season

• Type of Material: Article
• Authors: Melissa A. Rolfes, Centers for Disease Control and Prevention; Brendan Flannery, Centers for Disease Control and Prevention; Jessie R. Chung, Centers for Disease Control and Prevention; Alissa O'Halloran, Centers for Disease Control and Prevention; Shikha Garg, Centers for Disease Control and Prevention; Edward A. Belongia, Marshfield Clinic Research Foundation; Manjusha Gaglani, Texas A&M University; Richard K. Zimmerman, University of Pittsburgh; Michael L. Jackson, Kaiser Permanente Washington Health Research Institute; Arnold S. Monto, University of Michigan; Nisha B. Alden, Colorado Department of Public Health and Environment; Evan Anderson, Emory University; Nancy M. Bennett, University of Rochester; Laurie Billing, Ohio Department of Health; Seth Eckel, Michigan Department of Health and Human Services; Pam Daily Kirley, California Emerging Infections Program; Ruth Lynfield, Minnesota Department of Health; Maya L. Monroe, Maryland Department of Health and Mental Hygiene; Melanie Spencer, Salt Lake County Health Department; Nancy Spina, New York State Department of Health; H. Keipp Talbot, Vanderbilt University; Ann Thomas, Oregon Public Health Division; Salina M. Torres, New Mexico Department of Health; Kimberley Yousey-Hindes, Yale University; James A. Singleton, Centers for Disease Control and Prevention; Manish Patel, Centers for Disease Control and Prevention; Carrie Reed, Emory University; Alicia M. Fry, Centers for Disease Control and Prevention; Monica Farley, Emory University; P Ryan, Emory University
• Language: English
• Date: 2019-12-01
• Publisher: Oxford University Press Inc.
• Publication Version: Final Published Version
• Copyright Statement: © 2019 Oxford University Press.
• License: Creative Commons Attribution 4.0 International
• Final Published Version (URL): http://dx.doi.org/10.1093/cid/ciz075
• Title of Journal or Parent Work: Clinical Infectious Diseases
• Volume: 69
• Issue: 11
• Start Page: 1845
• End Page: 1853
• Grant/Funding Information: At the University of Pittsburgh, the project was also supported by the National Institutes of Health through grant UL1TR001857.; This work was supported by CDC through the following cooperative agreements: Emerging Infections Programs (CDC-RFA-CK17-1701), the Influenza Hospital Surveillance Project (5U38OT000143), the University of Michigan (1U01 IP001034), Kaiser Permanente Washington Research Institute (1U01 IP001037), Marshfield Clinic Research Institute (1U01 IP001038), University of Pittsburgh (1U01 IP001035), and Baylor Scott and White Healthcare (1U01 IP001039).
• Keywords: Vaccines recommendations; vaccination; burden; prevented illnesses; Adults; influenza; Parental report; Infectious Diseases; Immunization practices; Age; Care; Efficacy; Microbiology; Science & Technology; Life Sciences & Biomedicine; Prevention; Children; Advisory committee; Immunology
• Research Categories: Health Sciences, Immunology; Health Sciences, Epidemiology; Health Sciences, Public Health

Abstract

Background: The severity of the 2017-2018 influenza season in the United States was high, with influenza A(H3N2) viruses predominating. Here, we report influenza vaccine effectiveness (VE) and estimate the number of vaccine-prevented influenza-associated illnesses, medical visits, hospitalizations, and deaths for the 2017-2018 influenza season. Methods: We used national age-specific estimates of 2017-2018 influenza vaccine coverage and disease burden. We estimated VE against medically attended reverse-transcription polymerase chain reaction-confirmed influenza virus infection in the ambulatory setting using a test-negative design. We used a compartmental model to estimate numbers of influenza-associated outcomes prevented by vaccination. Results: The VE against outpatient, medically attended, laboratory-confirmed influenza was 38% (95% confidence interval [CI], 31%-43%), including 22% (95% CI, 12%-31%) against influenza A(H3N2), 62% (95% CI, 50%-71%) against influenza A(H1N1)pdm09, and 50% (95% CI, 41%-57%) against influenza B. We estimated that influenza vaccination prevented 7.1 million (95% CrI, 5.4 million-9.3 million) illnesses, 3.7 million (95% CrI, 2.8 million-4.9 million) medical visits, 109 000 (95% CrI, 39 000-231 000) hospitalizations, and 8000 (95% credible interval [CrI], 1100-21 000) deaths. Vaccination prevented 10% of expected hospitalizations overall and 41% among young children (6 months-4 years). Conclusions: Despite 38% VE, influenza vaccination reduced a substantial burden of influenza-associated illness, medical visits, hospitalizations, and deaths in the United States during the 2017-2018 season. Our results demonstrate the benefit of current influenza vaccination and the need for improved vaccines.