Seasonal flu activity is “elevated” in the U.S. and on the rise in most parts of the country, according to the latest update from the Centers for Disease Control and Prevention, which comes as the country is seeing elevated levels of COVID-19 and RSV activity as well.
The CDC estimates there have been at least 10 million illnesses, 110,000 hospitalizations and 6,500 deaths from flu so far this season, and reports that 17.5% of clinical lab tests were positive for influenza during the week ending Dec. 30, up from 16.6% the week prior.
Preliminary CDC data accessed Jan. 5 also shows that the majority of states (38) experienced a “high” or worse level of influenza-like illness activity during the week ending Dec. 30, with more than half of those states (21) described as having a “very high” level. Meanwhile, six states experienced “moderate” activity, according to the CDC, while another six experienced “minimal” or “low” levels.
“Influenza-like illness” refers to respiratory illness where a fever plus a cough or sore throat are present, which can include the flu as well as similar illnesses. Activity-level classifications correspond to 13 numeric levels and are based on percentages of outpatient visits due to this type of illness. At the state level, they reflect the “intensity” of such illness activity and not geographic spread, and the CDC says the underlying data may “disproportionally represent certain populations,” affecting the “full picture” of activity.
A majority of states (32) also saw their numeric ratings rise at least one level between the weeks ending Dec. 23 and Dec. 30, with the CDC reclassifying more than half of those states (20). Montana shot up from a classification of “minimal” to “high” in the week-over-week comparison, while Michigan and Utah rose from “moderate” to “high.” North Dakota and Iowa were the only two states that saw declines in their numeric ratings in that same period.
Preliminary outpatient surveillance data available through the CDC shows that 6.9% of roughly 2.3 million patient visits to a health care provider reported during the week ending Dec. 30 were for influenza-like illness. That’s up from the week prior when the share was 6.3% and remains more than twice as high as a national baseline of 2.9%. The CDC also reports that out of 10 regions of the U.S., all saw outpatient illness percentages above their respective baselines.
The CDC in recent weeks pointed to increased hospitalizations for influenza, COVID-19 and RSV while warning of low vaccination rates against those illnesses. Data available as of Jan. 5 showed that around 20,000 people with influenza were hospitalized during the week ending Dec. 30, up from about 15,000 the previous week and based on information from the thousands of hospitals reporting to the CDC’s National Healthcare Safety Network.
Relative to population, hospitalization rates for influenza rose from 4.5 to 6.1 per 100,000 people between the weeks ending Dec. 23 and Dec. 30, while the COVID-19 hospitalization rate was almost two times higher and rose from 8.7 to 10.5 per 100,000. The hospitalization rate for respiratory syncytial virus, known as RSV, declined from 3.4 to 2.1 per 100,000, based on data from a more limited hospital network across 12 states.
“RSV activity remains elevated in many areas of the country, though decreases have been observed in some areas,” the CDC said in a post on Friday. “Hospitalization rates remain elevated, particularly among young children and older adults.”
Separately, preliminary flu hospitalization rates available through the Influenza Hospitalization Surveillance Network show the 2023-2024 flu season didn’t start off with a bang like in the previous year. While the network represents around 9% of the population, it provides historical and demographic data related to influenza activity, and shows how rates can vary by race and ethnicity.
During the week ending Dec. 30, the CDC also received reports of seven pediatric flu-associated deaths, bringing the current total to 27 for the 2023-2024 season. There were 183 pediatric deaths during the last flu season.
To help prevent illness, hospitalization and death, the CDC recommends most people receive a flu vaccine, and offers a tool to help find local options.
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