Every state but Florida reported widespread influenza activity by the midpoint of the flu season in February, according to data from the Centers for Disease Control and Prevention.
“We can't predict the severity and duration of an influenza season, but the data suggest that we are nearing the peak,” Nancy Cox, Ph.D., said in a teleconference. The state of Florida had reported regional activity and the District of Columbia had reported local activity.
The percentage of people with flulike symptoms who tested positive for flu spiked in mid-February, but “we are within normal parameters of what we would expect,” said Dr. Cox, director of the influenza division at the CDC.
A total of 22 deaths in children with confirmed influenza had been reported to the CDC as of Feb. 22, based on data from the National Notifiable Diseases Surveillance System. Of these, 21 occurred between Dec. 24 and Feb. 10, Dr. Cox said. The number of flu-related deaths in children so far this year remains below the totals from the past 3 years, she added. The CDC does not track flu-related deaths in adults.
The H3N2 strain of influenza A has become the dominant strain for this year's flu season, said Dr. Cox. “The influenza season started out as mostly an H1N1 year through December and into the first part of January, and then it switched to H3N2,” she said.
As of Feb. 16, 14% of the more than 100,000 specimens tested since September 2007 have been positive for influenza. Of these, the majority (more than 84%) is influenza A; less than 16% is influenza B, said Dr. Cox.
Mainstream news reports of the mismatch between the influenza virus in the 2007–2008 vaccine and the virus that is circulating this year have caused concern among many people that their flu shots might not be effective, but vaccination can still provide protection, according to the CDC.
And, whether persons have been vaccinated or not, the CDC's take-home message remains the same: Good hand hygiene and cough etiquette also are important to prevent the spread of the disease.
For the latest information on the 2007–2008 flu season, visit www.cdc.gov/flu