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Flu vaccines lower risk of pneumonia and death among older adults living in care

Chan T, Fan-Ngai H, Ka-Hay LJ, Chu L, & Hon-Wai CF. Effectiveness of influenza vaccination in institutionalized older adults: A systematic review Journal of the American Medical Directors Association. 2014;15: 226.e1-6.

Review question

Do influenza (flu) vaccinations help lower risk of pneumonia and death among older adults who live in institutional care?

Background

The flu is a major cause of hospitalization and death among older adults who live in institutional care, such as nursing homes or in long term care.  The flu vaccine (‘flu shot’) could prevent the spread of flu infection and lower the risk of serious complications such as pneumonia and death.  It is hard to measure how effective the flu vaccine is among people in institutional care, since the most frail may not get the flu vaccine and may account for a larger number of the deaths and complications. Other studies may over-estimate the effectiveness of the flu vaccine by measuring death from all causes (not just influenza or its complications). This review aimed to control for these factors to measure the benefits of flu vaccination for older adults living in institutional care.

How the review was done

This is a review of 11 cohort and case control studies. The studies included 11,262 older adults in institutional care. Some people received the flu vaccine and others did not. The researchers measured the number of cases of flu-like illness, pneumonia, hospitalization and deaths due to influenza or pneumonia at least 3 months after the vaccination (one study measured effects for 3 months; 7 studies measured effects for 6 months; 3 studies measured effects for 1 year).

What the researchers found

The included studies were of medium or good quality. The vaccine was found to lower the risk of pneumonia and death from influenza or pneumonia and may also lower the risk of getting flu-like illnesses.  The vaccine is most effective when the vaccine strain matches the circulating influenza strains.

Conclusion

The influenza vaccine (flu shot) lowers the risk of serious complications from the flu (death and pneumonia) and is recommended for older adults living in institutional care.