THURSDAY, Oct. 14, 2004 (HealthDayNews) -- While U.S. health officials say it's too soon to predict the severity of the coming flu season, unofficial accounts indicate it could be relatively harsh.
If that proves true, it could leave health-care providers scrambling. They are already reeling from the surprise announcement last week that British regulators had suspended the license of a firm that had been expected to produce nearly half of the United States' anticipated 100 million to 105 million vaccine doses.
"We just don't know yet how serious the flu epidemic is going to be," Dr. Julie Gerberding, director of the U.S. Centers for Disease Control and Prevention, said at a news conference on Tuesday.
Dr. Anne Moscona, a professor of pediatrics at Mount Sinai School of Medicine in New York City, agreed. "Unfortunately, there's no way to predict. There are isolated cases, but there has not been any rapid spread or epidemic. That's typical for this time of year."
But other experts said there have been some worrisome early signs, gleaned from a handful of small outbreaks in a few states. While there are several factors that help dictate how bad a flu season will be, one of the most important is which flu strain is predominant that year.
So far, laboratories have confirmed that the H3N2 strain is out and about. The bad news is that H3N2 tends to be more severe than the other two strains that typically circulate in humans, said Dr. Jonathan McCullers, an infectious disease expert with St. Jude Children's Research Hospital in Memphis, Tenn.
"If that's the predominant one that circulates all year, I would expect to see the higher end of hospitalization and mortality because that's what we've seen in the past regardless of vaccine match," McCullers said.
The good news is that the H3N2 strain seen so far this year matches the vaccine that has been produced.
However, expected vaccine supplies were cut in half last week by British health regulators' decision to suspend the license of California-based Chiron Corp., whose manufacturing plant is located outside of Liverpool, England. Bacterial contamination forced the suspension, the regulators said. Chiron was one of only two companies supplying the U.S. market with flu vaccine this year.
The other major supplier, Aventis Pasteur, had 22.4 million doses still unshipped when Chiron's license was suspended.
To compensate for the shortfall, U.S. health officials and Aventis announced Tuesday a plan to steer the remaining flu doses that have yet to be shipped to the areas and the people who need them most.
"Our overall goal is to target the vaccine to the people who will get the most benefit, and to do it in a way that is fair and equitable to the greatest number of people," Gerberding said at the news conference.
She is asking healthy Americans to forgo a flu shot so there is enough vaccine for high-risk individuals, including the very young, the elderly and the chronically ill.
Gerberding estimated that 42 million to 50 million people will meet the CDC's high-risk criteria and will request a vaccination. Aventis is producing 55 million doses of shots, 33 million of which have been shipped. There also will be another 1 million doses of FluMist, an intranasal vaccine.
Over the next six to eight weeks, about 14.2 million doses of the unshipped Aventis supply will be allocated to high-priority providers, such as hospitals, long-term care facilities, nursing homes and private providers who care for young children. High-risk children, people over the age of 65, and Veterans Administration facilities are on the CDC's list of high-priority groups to receive the "first wave" of vaccine, Gerberding said.
Last year was a worse-than-usual flu season, according to the CDC. As of May 31, 2004, there had been reports from 40 states of 152 flu-related deaths among children, the first year such figures were kept.
Every year in the United States, an estimated 5 percent to 20 percent of the population gets the flu. More than 200,000 people are hospitalized from flu complications, and approximately 36,000 people die from the illness, according to the CDC.
Despite the vaccine shortage, health experts say the doses produced for this year are a good match for the H3N2 strain.
"The type of influenza virus that is around the most so far is a type that can cause serious disease but it's covered by the vaccine," said Dr. George Pankey, director of infectious disease research at the Ochsner Clinic Foundation in New Orleans.
McCullers noted that in any given year, only a proportion of high-risk individuals are vaccinated.
"The vaccine supply is rather small in comparison to the population of the U.S.," he said. "Even if we had the other 50 million doses, that's not going to make that big an impact on healthy people. The impact is if we're unable to get the vaccine to high-risk people."
And, of course, there's the inescapable fact that the flu season has not yet started in earnest, leaving experts with little information on which to base forecasts.
"You still have to worry about the possibility that it could be a bad year," Pankey said. "It's kind of like predicting hurricanes... These things can pop out all of a sudden and you'll see a whole rash."
More information
The U.S. Centers for Disease Control and Prevention has more on the flu and flu vaccine.
