On Monday, the Centers for Disease Control and Prevention reported 43 states are having widespread flu activity. That's up from 36 states last week.
This week, six more children have died after having the flu, the CDC said. That brings the total number of pediatric deaths
to 21 so far for this flu season.
It is unclear how many adults have died from the flu. States are not required to report
individual seasonal flu cases or deaths of people who are older than 18. Using statistical models, the CDC estimates the number of people who die from the flu each year can range from about 3,000 to as high as 49,000 people.
While flu activity is high, the number of cases did drop from last week's epidemic level. The CDC notes that a typical flu season has different waves of intensity.
Experts had anticipated a severe flu season
this year because of a mismatch of strains
in the flu vaccine.
That's because one of the flu viruses mutated, and it was the H3N2 strain that has accounted for 95% of flu cases so far this year. "For a regular flu season, H3N2 seasons are more severe," said CDC spokesperson Erin Burns.
H3N2 is typically associated with higher rates of complications and hospitalizations. Children and the elderly often have more intense reactions to the virus.
In intense H3N2 seasons, the CDC estimates that 28,909 people die from the flu compared with 10,648 deaths from non-H3N2 seasons.
During 2012-2013, the last H3N2 prevalent season, pneumonia and influenza related deaths peaked to 9.9%.
So far this season, the high has reached is 6.8%. The rate of flu-related hospitalizations has increased by over 40% since the same time last year, but the numbers are in line with the 2012-2013 season.
Despite the mismatched vaccine, the CDC says the best way to fight the flu is to get vaccinated. Experts say that flu vaccine can reduce the risk of doctor's visits by about 60%, and even a mismatched vaccine can still provide some protection. According to Burns, the 2003-2004 season was similar to this year's with mutated strains of H3N2 occurring, and the vaccine was still 43% effective.
"Of course, everyone would love to have a better fit, but it still provides some immunity," said Dr. Lisa Thebner, a pediatrician in New York City.
If you start to feel like you are getting the flu,
symptoms include fever, sore throat, coughing and body aches. It's important to go to a doctor and get a prescription for antiviral medication. Tamiflu and Relenza have been considered most effective at reducing complications when given soon after symptoms start.