More flu shots in adults means less flu risk in seniors

By John Murphy, MDLinx
Published December 8, 2015

Key Takeaways

In areas of the U.S. where vaccination rates were higher among adults (18-64 year olds), the odds of influenza-related illness was lower for seniors (age 65 and older), according to a study published online September 9, 2015 in Clinical Infectious Diseases.

In this nationwide analysis of more than 3 million Americans across 8 flu seasons, researchers observed that seniors who lived in counties where at least 31% of 18-to-64-year-olds were immunized against flu had a 21% lower chance of being diagnosed with a flu-related illness.

“Our findings suggest that flu vaccination should be encouraged among low-risk adults not just for their own benefit, but also for the benefit of higher risk adults in their community, such as the elderly,” said study author Glen B. Taksler, PhD, of the Cleveland Clinic in Cleveland, OH. “In round numbers, we estimated that about 1 in 20 cases of influenza-related illness in the elderly could have been prevented if more non-elderly adults had received the flu vaccine.”

Older adults have the highest influenza-related morbidity and mortality risk, yet the influenza vaccine is less effective in them. However, this analysis found that seniors who were vaccinated themselves had more than twice the reduction in risk compared with unvaccinated older adults, which suggests that community-wide vaccination may boost the protection provided by individual vaccination, the researchers speculated.

The study results found no direct association between vaccine coverage among children and flu illness in the elderly, which suggests that seniors benefit most from vaccination of other adults, with whom they are more likely to have direct contact. 

The Centers for Disease Control and Prevention recommends that everyone 6 months of age and older get a flu shot every season, yet only about 37% of 18-64 year-old adults were vaccinated in the 2013-2014 season.

“Our findings suggest that young, healthy persons who obtain vaccination may also protect higher-risk individuals in their community, with the potential to prevent up to 5.9% of influenza diagnoses in elderly individuals,” the authors concluded.

For more information visit the MDLinx Influenza Resource Center.

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