(NEXSTAR) – Cases of the flu continue to mount, with health officials recently recording the first pediatric flu-related deaths of the season, but some states are seeing much higher activity than others.
According to data released Friday by the Centers for Disease Control and Prevention, the hospitalization rate nationwide jumped by 14.3%, with over 9,900 people admitted with the flu.
“Colorado, Louisiana and New York are [states] that are experiencing really fast increases in influenza,” Dr. Andrew Pekosz, an infectious disease specialist with the Johns Hopkins Bloomberg School of Public Health, said Tuesday during a public health media briefing.
New Jersey, Rhode Island and Louisiana are also experiencing “very high” levels of flu activity according to the latest data, for the week ending Dec. 13. The CDC also found high activity in New Mexico, Idaho, Michigan, North Carolina, South Carolina, Georgia, Washington D.C., Connecticut, Maryland and Massachusetts.
The CDC notes that the map is based on the proportion of healthcare visits for influenza-like illness, and doesn’t measure the geographic spread of the virus, so it is possible that an outbreak in one or more cities might disproportionately show an entire state having high flu activity.
Pekosz says the data shows that the “super flu” strain, or subclade K, is spreading everywhere that influenza is. Lab tests found that 89.8% of 216 influenza A viruses collected since Sept. 28 were positive for the subclade K, according to the CDC.
This strain of influenza A, which historically causes the most deaths in older people, is not included in the vaccine this year, making some experts worried it could contribute to an especially bad flu season.
Flu seasons often don’t peak until around February, so it’s too early to know how big a problem that mismatch will be.
“By the end of the flu season, in the next 2 to 3 months, every state will experience high amounts of influenza activity,” Pekosz said. “We just don’t know exactly when each state will start and end in terms of those outbreaks.”
The CDC recommends that everyone 6 months and older get an annual vaccination, and public health experts say it’s not too late. About 42% of U.S. adults and 41% of children have gotten flu shots this season, according to CDC data.
The shots may not prevent all symptoms but they can prevent many infections from becoming severe. That appears to be true for this year’s shot, according to a preliminary U.K. analysis.
The Associated Press contributed to this report.
