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Health

Flu season winds down with a whimper

This year's season was mild and resulted in fewer deaths, thanks in part to a good vaccine match, experts say.

By ASSOCIATED PRESS
Published April 28, 2006

ATLANTA - This year's flu season draws to a close as one of the mildest in recent years, partly because the vaccine was a good match for this winter's most common viruses.

Overall, there were fewer flu and pneumonia deaths than during a typical flu season, and health officials say fewer than two dozen children's deaths were reported.

The one exception was a nasty outbreak of a different flu virus that hospitalized more than 30 children in Houston.

In about half of the states, reports of flulike illness are sporadic or virtually nonexistent now, according to the U.S. Centers for Disease Control and Prevention.

"Flu season is pretty much over," said David Engelthaler, Arizona's state epidemiologist.

Flu was widespread in only five states - Connecticut, Delaware, Indiana, New York and Rhode Island - the week of April 9-15, the most recent data available.

The long-lasting season started in December with a rush of cases in the Southwest that swamped hospital emergency rooms. It then rotated to other regions, with widespread activity in some areas as late as this month.

But overall, the season has been mild, said Dr. Roland Levandowski of the National Institute of Allergy and Infectious Diseases.

One indicator is the nasal and throat specimens taken from patients with flu symptoms by physicians who are part of a national flu surveillance network.

Between the beginning of October and April 15, 13 percent of specimens tested positive for flu. For roughly the same period a year ago, it was 16 percent and in 2003-04, 20 percent.

Another indicator is deaths. The severe 2003-04 season started with the flu-related deaths of 93 children between that October and early January. Overall, deaths from pneumonia and flu were considered epidemic for nine consecutive weeks that winter.

This season, the number of deaths was lower than normal. One possible reason: The vaccine seems to be doing the job.

Flu viruses are categorized by types: Type A, found in animals and people, and Type B, normally found only in humans.

Last year, health officials - making essentially an educated guess - formulated the vaccine against three flu viruses. They were Type A New Caledonia, Type A California and Type B Shanghai.

Test results show 84 percent of people with confirmed flu this season had a Type A flu, and the rest had a Type B. Of the patients who had Type A viruses, about 80 percent or more had viruses identical or similar to the A bugs in the vaccine.

Good, but not perfect: The B virus was not a good match.

Nearly 70 percent of the people who tested positive for a B virus had Type B Victoria, a version not found in the vaccine. For adults, that wasn't a big deal because they've been exposed to both lineages of B flu through the years and could muster an immune response.

But for some children never exposed to Type B Victoria, the result was more serious.

Since mid January, 31 children have been sent to Texas Children's Hospital in Houston for treatment of Type B Victoria flu.

WASHINGTON - If a worldwide flu epidemic strikes, face masks should be considered a defense of last resort, since there's little evidence that the masks available to the average person or most health care workers can prevent influenza infection, the Institute of Medicine said Thursday.

Yet if a flu pandemic begins, the millions who undoubtedly will use masks in hopes of protection will need a large supply because the masks shouldn't be used more than once, concluded the institute, an arm of the National Academies, the nation's most prestigious science organization.

Anticipating a huge demand if the bird flu or some super strain of influenza sparks the next pandemic, federal health officials asked the institute to determine whether there are masks that could be reused safely.

BY HAND: Someone sneezes into his hand and then grabs a doorknob that you touch, or he shakes your hand.

BY LARGE DROPLETS OF VIRUS, IF SOMEONE IS IN THE DIRECT PATH OF A SNEEZE OR A COUGH: Those heavy droplets fall quickly to the ground.

BY TINY PARTICLES: The particles can stay suspended in the air for far longer periods.

[Last modified April 28, 2006, 01:17:12]