Mortality rate reaches epidemic levels
According to the CDC's latest report, which includes data through Jan. 11, influenza-like illness activity is high in 14 states: Alabama, Arkansas, Idaho, Kansas, Louisiana, Mississippi, Missouri, Nevada, New Mexico, Oklahoma, Oregon, Tennessee, Texas, and Virginia. That's down from 20 states in the CDC's last report, which tracked influenza across week 1 of 2014.
However, this flu season has gotten more deadly: From Jan. 5 to Jan. 11, 7.5% of U.S. deaths were due to pneumonia and influenza, exceeding the 7.2% epidemic threshold for week 2.
In California, where influenza activity levels remain low, health officials have confirmed 45 flu-related deaths this season, and they estimate that about 50 more deaths may be caused by the illness so far. This time last year, the state had only confirmed five deaths for the flu season.
"This appears to be a pretty severe season in terms of looking at mortality as a measure of severity," says California Department of Public Health epidemiologist Gil Chavez.
Chavez said CDPH is hopeful that the spread of the virus will taper as more residents get vaccinated—which is "foremost in our agenda"—and seek treatment for flu symptoms.
"What we don't know is if this is going to abate and we have equal mortality rates that just happened to peak early," Chavez said, adding "but as of now, we can certainly say that this is a season that started sooner."
Young, healthy Americans are disproportionally affected
Although young children and older adults generally are most vulnerable to the flu, 61% of the patients hospitalized for flu-related illnesses this season were between 18 and 64 years old.
Experts say the unusually high number of adults being infected is because the predominant strain of flu is H1N1. (Reminder: The H1N1 strain is the same strain that was responsible for as many as 203,000 deaths worldwide during the 2009 pandemic.)