Flu Shots Reduce Deaths And Hospital Visits In The Elderly, New Study

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Main Category: Flu / Cold / SARS
Also Included In: Seniors / Aging
Article Date: 04 Oct 2007 - 4:00 PDT

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A new US study has shown that flu vaccination is effective at cutting rates of hospitalization and death among community dwelling elderly people.

The study is published in the New England Journal of Medicine (NEJM) and is the work of Dr Kristin L Nichol, chief of medicine at the VA Medical Center in Minneapolis, Minnesota, and colleagues.

Although yearly flu shots are recommended in the US for older people, the take up rate falls far short of the nation's target of 90 per cent; only about 60 per cent of elderly Americans have their annual flu shot.

This is the first long term multicentre study to examine the effectiveness of flu shots across a range of elderly people in geographically diverse regions. Previous studies have been short term (over one or two seasons) and at single sites.

Nichol and colleagues analysed vaccination status data totalling 713,872 person-seasons on 18 cohorts of people aged 65 and over from three HMOs (health maintenance organizations).

One HMO data set covered Minnesota/Wisconsin for 1990-1991 through 1999-2000, another covered New York for 1996-1997 through 1999-2000, and the third covered Oregon/Washington for 1996-1997 through 1999-2000.

The results showed that:

• There was a 27 per cent reduction in rates of hospitalization among those people who had a flu vaccination compared to those who did not.
• The effect of having a vaccination also reduced the rate of death from any cause by 48 per cent.
• The figures were generally stable across age groups and risk categories.
• And they were still significant, although at a lower level, when the researchers took into account factors that could have caused the figures to be inflated, such as the fact healthier elderly people are more likely to be vaccinated than sick, weaker elderly people.

The researchers concluded that:

"During 10 seasons, influenza vaccination was associated with significant reductions in the risk of hospitalization for pneumonia or influenza and in the risk of death among community-dwelling elderly persons. Vaccine delivery to this high-priority group should be improved."

Commenting in Journal Watch Infectious Diseases, Dr Neil R Blacklow said that this study:

"Counters concerns that previous findings of vaccine effectiveness might have been influenced by characteristics unique to a single influenza season or a localized study population."

However, he points out, as does Dr John D Treanor in an editorial published in the same NEJM issue as the study, that current vaccines are probably less protective against the flu in the elderly than in younger adults and that more protective vaccines are needed to treat older people.

But he also said that having enhanced vaccination programmes targeted at children could reduce the spread of flu and thereby give secondary protection to the elderly. This is what happened with pneumococcal vaccines.

Nichol told WebMD that the study does not claim that the flu vaccine is perfect, or that the search for better alternatives should stop:

"What it does say is right now, even as we are exploring other options, current vaccines have something very important to offer older adults," said Nichol.

"Effectiveness of Influenza Vaccine in the Community-Dwelling Elderly."
Nichol, Kristin L., Nordin, James D., Nelson, David B., Mullooly, John P., Hak, Eelko
N Engl J Med 2007 357: 1373-1381
Volume 357:1373-1381, October 4, 2007, Number 14

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Written by: Catharine Paddock
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