Flu shot doesn't need perfect virus match, study says

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Flu shot doesn't need perfect virus match, study says

By Gene Emery

BOSTON (Reuters) - The annual influenza vaccine can protect against

illness even if it isn't perfectly attuned to the flu strain going

around, researchers said in a finding that may have implications for

protecting people against bird flu.

Flu viruses mutate over time, a process called " drift. " So viruses

that sweep across the country may not always be those selected each

February as the basis for the annual vaccine.

The study, to be published in Thursday's New England Journal of

Medicine, found that the flu vaccine works even when drift has occurred.

Suzanne Ohmit of the University of Michigan School of Public Health

and her colleagues found that in the fall of 2004, Sanofi-Pasteur's

FluZone vaccine was 77 percent effective and MedImmune Inc.'s Flumist

worked in 57 percent of the cases even though the flu strain making

the rounds that year was not selected for the vaccine.

" We were surprised to learn that it worked as well as it did in a year

when we might have thought it would have been less effective, " said

Arnold Monto of the University of Michigan School of Public Health,

another member of the team. " It is ideal to have a vaccine match what

is circulating. But even when it doesn't match exactly, you can get

protection. "

Monto told Reuters that the finding carries lessons for treating the

predicted bird flu pandemic. Researchers are working on a vaccine, but

there is no guarantee that the virus will match the strain that causes

an outbreak.

Instead of stockpiling the vaccine, it might be wise to start

inoculating people now, he said.

'PRIME THE PUMP'

Bird flu is expected to be so novel nobody will have any immunity to

it, said Monto. As a result, people are going to need two doses of the

vaccine, just as children who have never been exposed to regular

influenza need two doses of the flu vaccine to be protected.

" Because we're all naive to this and we're going to be all like little

children, " he said, " it may be wise for us to get the first shot of

whatever's available, which may give us some protection and will, in

that case, prime the pump " and make inoculation more effective when a

properly tuned vaccine is distributed.

A second team of investigators, also reporting in the Journal, said

that when school-age children are vaccinated against the flu, it

blocks the spread of illness to others.

King of the University of land and his colleagues gave the

inhaled Flumist vaccine to nearly half the children in schools in

land, Texas, Minnesota and Washington state a year ago. MedImmune

sponsored the test.

While 52 percent of the children developed a fever or flu-like illness

in the schools where the vaccines weren't given, the rate was 40

percent in the schools where many of the youngsters were vaccinated. A

similar decline in illness was seen in the adults in those families.

" Despite vaccinating less than half the kids, we showed an impact on

all the families in that school, not just the targeted kid, " King told

Reuters.

He said universal vaccination of healthy youngsters in elementary

school should be strongly considered.

" You're protecting the kids but more importantly you're protecting the

families and communities, " he said.

King added that school-based vaccination programs would also create a

system making it easier to vaccinate the rest of the population if a

bird flu pandemic loomed.

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