High flu levels remain in California. How do states compare?

Flu-like activity has now reached “very high” levels in 30 states, an increase of 10 more states than the previous week, according to the latest update by the U.S. Centers for Disease Control and Prevention. The CDC for the first time is calling the 2025-26 influenza season “moderately severe,” taking into account flu-related outpatient visits, hospitalizations and deaths. In California, levels were reported at the top of the “high” scale for the week that ended on Dec. 27. That was a change from the bottom of the “high” scale one week prior, and from “moderate” levels two weeks ago. (Previous coverage in the video above.)The CDC now estimates that there have been at least 11 million illnesses, 120,000 hospitalizations and 5,000 deaths so far this season. There have been at least nine child deaths, according to the CDC. The tally was updated to include one child flu-related death that was recently reported in Sacramento County. About 8.2% of visits to a health care provider were for a respiratory illness, which represents an increase, the CDC said. Just four states were rated in “moderate” or “low” categories for flu levels. California’s Department of Public Health has reported that seasonal flu activity is increasing in all regions of the state, with a notable rise in test positivity among children. Hospitalizations are low but expected to increase, according to the state. A variant known as subclade K is believed to be driving the latest increase in flu cases. Subclade K is a variant of the H3N2 strain. That strain can lead to more severe cases in older adults. It’s not clear if subclade K is just spread more easily or is also more dangerous, the AP reported. The flu is particularly dangerous for people 65 and older, pregnant women, young children and those with chronic health problems, including asthma, diabetes, heart disease and weak immune systems.The CDC and most medical societies recommend that people ages 6 months and older get a flu shot. The Associated Press reported that the flu vaccine isn’t a perfect match to subclade K but that health experts still believe it could offer at least partial protection. About 42% of adults and children have gotten a flu shot so far this year, according to the CDC.Below are possible flu symptoms:FeverCoughSore throatRunny or stuffy noseMuscle or body achesHeadachesFatigue (tiredness)Vomiting and diarrheaThe following steps can also be taken to reduce the likelihood of contracting the flu and other respiratory illnesses:Wash hands thoroughly and frequently.Cover coughs and sneezes.Stay home from work or school when sick.Consider indoor masking in crowded places.Improve ventilation by opening windows or moving events outdoors.Disinfect frequently used surfaces. See more information on flu activity by state in the chart below. Jonathan Ayestas and The Associated Press contributed to this story. See more coverage of top California stories here | Download our app | Subscribe to our morning newsletter | Find us on YouTube here and subscribe to our channelPHNjcmlwdCB0eXBlPSJ0ZXh0L2phdmFzY3JpcHQiPiFmdW5jdGlvbigpeyJ1c2Ugc3RyaWN0Ijt3aW5kb3cuYWRkRXZlbnRMaXN0ZW5lcigibWVzc2FnZSIsKGZ1bmN0aW9uKGUpe2lmKHZvaWQgMCE9PWUuZGF0YVsiZGF0YXdyYXBwZXItaGVpZ2h0Il0pe3ZhciB0PWRvY3VtZW50LnF1ZXJ5U2VsZWN0b3JBbGwoImlmcmFtZSIpO2Zvcih2YXIgYSBpbiBlLmRhdGFbImRhdGF3cmFwcGVyLWhlaWdodCJdKWZvcih2YXIgcj0wO3I8dC5sZW5ndGg7cisrKXtpZih0W3JdLmNvbnRlbnRXaW5kb3c9PT1lLnNvdXJjZSl0W3JdLnN0eWxlLmhlaWdodD1lLmRhdGFbImRhdGF3cmFwcGVyLWhlaWdodCJdW2FdKyJweCJ9fX0pKX0oKTs8L3NjcmlwdD4=

Flu-like activity has now reached “very high” levels in 30 states, an increase of 10 more states than the previous week, according to the latest update by the U.S. Centers for Disease Control and Prevention.

The CDC for the first time is calling the 2025-26 influenza season “moderately severe,” taking into account flu-related outpatient visits, hospitalizations and deaths.

In California, levels were reported at the top of the “high” scale for the week that ended on Dec. 27. That was a change from the bottom of the “high” scale one week prior, and from “moderate” levels two weeks ago.

(Previous coverage in the video above.)

The CDC now estimates that there have been at least 11 million illnesses, 120,000 hospitalizations and 5,000 deaths so far this season. There have been at least nine child deaths, according to the CDC. The tally was updated to include one child flu-related death that was recently reported in Sacramento County.

About 8.2% of visits to a health care provider were for a respiratory illness, which represents an increase, the CDC said.

Just four states were rated in “moderate” or “low” categories for flu levels.

California’s Department of Public Health has reported that seasonal flu activity is increasing in all regions of the state, with a notable rise in test positivity among children. Hospitalizations are low but expected to increase, according to the state.

A variant known as subclade K is believed to be driving the latest increase in flu cases.

Subclade K is a variant of the H3N2 strain. That strain can lead to more severe cases in older adults. It’s not clear if subclade K is just spread more easily or is also more dangerous, the AP reported.

The flu is particularly dangerous for people 65 and older, pregnant women, young children and those with chronic health problems, including asthma, diabetes, heart disease and weak immune systems.

The CDC and most medical societies recommend that people ages 6 months and older get a flu shot.

The Associated Press reported that the flu vaccine isn’t a perfect match to subclade K but that health experts still believe it could offer at least partial protection. About 42% of adults and children have gotten a flu shot so far this year, according to the CDC.

Below are possible flu symptoms:

FeverCoughSore throatRunny or stuffy noseMuscle or body achesHeadachesFatigue (tiredness)Vomiting and diarrhea

The following steps can also be taken to reduce the likelihood of contracting the flu and other respiratory illnesses:

Wash hands thoroughly and frequently.Cover coughs and sneezes.Stay home from work or school when sick.Consider indoor masking in crowded places.Improve ventilation by opening windows or moving events outdoors.Disinfect frequently used surfaces.

See more information on flu activity by state in the chart below.

Jonathan Ayestas and The Associated Press contributed to this story.

See more coverage of top California stories here | Download our app | Subscribe to our morning newsletter | Find us on YouTube here and subscribe to our channel