Send to

Choose Destination
Vaccine. 2018 Feb 28;36(10):1272-1278. doi: 10.1016/j.vaccine.2018.01.045.

Influenza vaccine effectiveness in older adults compared with younger adults over five seasons.

Author information

Epidemic Intelligence Service, CDC, United States; Influenza Division, National Center for Immunization and Respiratory Diseases, CDC, United States. Electronic address:
Influenza Division, National Center for Immunization and Respiratory Diseases, CDC, United States.
University of Michigan and Henry Ford Health System, United States.
Marshfield Clinic Research Institute, United States.
Baylor Scott and White Health, Texas A&M University Health Science Center College of Medicine, United States.
University of Pittsburgh Schools of the Health Sciences and UPMC, United States.
Kaiser Permanente Washington Health Research Institute, United States.



There have been inconsistent reports of decreased vaccine effectiveness (VE) against influenza viruses among older adults (aged ≥ 65 years) compared with younger adults in the United States. A direct comparison of VE over multiple seasons is needed to assess the consistency of these observations.


We performed a pooled analysis of VE over 5 seasons among adults aged ≥ 18 years who were systematically enrolled in the U.S. Flu VE Network. Outpatients with medically-attended acute respiratory illness (cough with illness onset ≤ 7 days prior to enrollment) were tested for influenza by reverse transcription polymerase chain reaction. We compared differences in VE and vaccine failures among older adult age group (65-74, ≥75, and ≥ 65 years) to adults aged 18-49 years by influenza type and subtype using interaction terms to test for statistical significance and stratified by prior season vaccination status.


Analysis included 20,022 adults aged ≥ 18 years enrolled during the 2011-12 through 2015-16 influenza seasons; 4,785 (24%) tested positive for influenza. VE among patients aged ≥ 65 years was not significantly lower than VE among patients aged 18-49 years against any subtype with no significant interaction of age and vaccination. VE against A(H3N2) viruses was 14% (95% confidence interval [CI] -14% to 36%) for adults ≥ 65 years and 21% (CI 9-32%) for adults 18-49 years. VE against A(H1N1)pdm09 was 49% (95% CI 22-66%) for adults ≥ 65 years and 48% (95% CI 41-54%) for adults 18-49 years and against B viruses was 62% (95% CI 44-74%) for adults ≥ 65 years and 55% (95% CI 45-63%) for adults 18-49 years. There was no significant interaction of age and vaccination for separate strata of prior vaccination status.


Over 5 seasons, influenza vaccination provided similar levels of protection among older and younger adults, with lower levels of protection against influenza A(H3N2) in all ages.


Human; Influenza; Influenza vaccine effectiveness; Influenza vaccines; Older adults

[Indexed for MEDLINE]
Free PMC Article

Supplemental Content

Full text links

Icon for Elsevier Science Icon for PubMed Central
Loading ...
Support Center