Flu shot research has implications for bird flu

SCIENCE NEWS
December 13, 2006
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.

James King of the University of Maryland and his colleagues gave the inhaled Flumist vaccine to nearly half the children in schools in Maryland, 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.