© Charles Krupa, AP
Flu is now widespread in 46 states and has killed 26 children, health officials said today.
"This year is shaping up to be a bad one, particularly for people 65 and older," says Thomas Frieden, director of the Centers for Disease Control and Prevention. Children younger than 5 are also at high risk of hospitalization, particularly babies under 6 months, who are too young to be vaccinated.
Flu is hitting the USA especially hard this year for two reasons.
First, the dominant flu strain in circulation is H3N2, a type that tends to cause twice as many hospitalizations and deaths as other strains of flu, Frieden says. Hospitalization rates have risen to 92 per 100,000 people, compared with 52 hospitalizations per 100,000 in a typical year.
"H3N2 is a nastier flu virus than other flu viruses," Frieden says. "Hospitalization rates in the over-65 age group are rising."
Second, the H3N2 viruses used to make this year's influenza vaccines aren't a good match to those spreading throughout the country, the CDC says. That's because about two-thirds of the H3N2 viruses in circulation have mutated significantly since vaccine production began last spring. Drugmakers tend to start making flu vaccines in the spring, in order to produce enough for the fall flu season.
"Even in a good year, the flu vaccine is not as effective as our other vaccines," Frieden says, noting that flu efficacy rates are about 60% to 65%.
Frieden says there are several ways for people to protect themselves.