Montreal Gazette

This year’s flu vaccine

provided little protection to people 65 and older who got a shot.

- HELEN BRANSWELL THE CANADIAN PRESS

TORONTO — This year’s flu vaccine provided little protection to people 65 and older who got a shot, new data released by the U.S. Centers for Disease Control reveal.

The study estimates how well the vaccine did at preventing people from becoming sick enough to need to see a doctor. And the data suggest this year the vaccine didn’t perform very well for older adults.

It found that a flu shot cut an older adult’s risk of contractin­g a case of influenza A H3N2 that needed medical care by only nine per cent.

When the scientists calculated the overall effectiven­ess — the vaccine’s ability to prevent medically attended flu caused by both flu A and B viruses — the estimate was 27 per cent for older adults.

The findings are disappoint­ing given the H3N2 component in this year’s vaccine is well matched to the viruses circulatin­g. Paradoxica­lly, the B component of the vaccine isn’t as closely matched to circulatin­g viruses, yet it is performing better, according to the study.

Dr. Joe Bresee, a flu expert with the CDC, said older adults need to know that if they got a flu shot and they develop flu-like illness, they may have influenza and should see a doctor to determine if they should take antiviral drugs.

“We wanted to make sure that people knew that … because we still want to communicat­e the fact that if you do get sick, get antivirals. And don’t assume just because you got the vaccine, that the flu-like illness you’ve got can’t be flu,” said Bresee, who heads the CDC flu division’s epidemiolo­gy team.

This type of study may actually overestima­te the effectiven­ess of the vaccine, some experts say. It cannot capture a picture of what percentage of people got a shot and got the flu but didn’t see a doctor. Most people simply ride out a case of the flu in bed.

As well, it doesn’t account for people who become so sick they go directly to hospital, which would not be uncommon in elderly people.

The findings are an interim estimate, based on data gathered during the middle of the flu season. The researcher­s are continuing to gather data and will run a final analysis at the end of the season.

The numbers may change slightly in the final analy- sis; in this run-through, the overall vaccine effectiven­ess figure dropped to 56 per cent from 62 per cent in an analysis conducted in January.

But Bresee suggested the figures are probably an accurate reflection of the vaccine’s performanc­e in older adults.

Even in younger adults and children, the study suggests this year’s vaccine offered modest protection. Bresee described it as “moderate” and said it’s a word people in the flu world are starting to realize seems to apply to flu vaccines.

Even in young adults — the group which typically mounts the best immune response to flu vaccine — the performanc­e of this year’s vaccine was not stellar.

In people aged 17 to 49, it cut the risk of medically attended flu by 52 per cent overall. But for the H3N2 component, the protection was only 46 per cent in this age group.

Dr. Danuta Skowronski, a flu expert with the British Columbia Centre for Disease Control, said the findings are consistent with Canadian and European vaccine effectiven­ess estimates released in recent weeks.

For Canada, the H3N2 effectiven­ess rate was 45 per cent, she noted, while European investigat­ors pegged the effectiven­ess against that component at 42 per cent.

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 ?? THE CANADIAN PRESS ?? Data suggest this year’s flu shot didn’t perform very well for older adults.
THE CANADIAN PRESS Data suggest this year’s flu shot didn’t perform very well for older adults.

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