Respiratory illness visits and influenza hospitalizations are escalating across most of the country, with activity “expected to continue for several weeks,” according to surveillance data released Monday by the Centers for Disease Control and Prevention.
For the week ended Dec. 27, 45 states are showing “high” or “very high” levels of outpatient respiratory illness activity.
About 8.2% of outpatient visits are for respiratory illnesses, well above the 3.1% baseline and higher than any prior year since 1997 (the earliest reported by CDC) at this point in the season. The percentage has risen steeply from the prior week’s 6% and the two weeks prior’s 4.1%.
Emergency department visits with a discharge diagnosis of influenza also reached a season high 8.3% for that week, nearing last season’s peak of 8.4% but already ahead of the two seasons before that.
Among the nation’s hospitals, the CDC reported 33,301 admissions for influenza during the week ended Dec. 27, up from 19,053 the week prior.
The rate of lab-confirmed influenza hospitalizations reported to the CDC rose from 7.6 per 100,000 people to 8.4 per 100,000 people. Cumulatively through the season, that metric increases to 28.1 per 100,000 people, the third-highest rate since 2009, behind the 2022-2023 (53.4 per 100,000) and 2023-2024 (29.2 per 100,000) seasons.
All told, the public health agency estimates there have been at least 11 million illnesses, 120,000 hospitalizations, and 5,000 deaths as of Dec. 27, as well as the reported deaths of nine children from influenza.
The season’s increasing severity has led some hospitals and health systems to take precautionary steps, such as the implementation of masking policies. Mass General Brigham, based in Massachusetts, where the CDC considers flu activity to be “very high,” has its care teams and other staff wearing face masks during interactions in patient rooms as of Dec. 29, according to its website. Brown University Health, in Rhode Island, said it would begin a similar policy starting Jan. 6 due to high nearby community, ED and hospital activity.
Influenza A (H3N2) has made up the bulk of flu viruses tested by public health labs, and among a subset of those further tested nearly all were subclade K. The variant has been attributed to the relatively early flu seasons seen this year in some other countries, but emerged in prominence after experts selected the composition of this season’s vaccines.
Still, the CDC recommends that everyone aged 6 months or older who has not been vaccinated this season to do so, adding that about 130 million doses of flu vaccine have been distributed this season so far.
CDC’s data also show that about 42% of children nationwide have been vaccinated as of mid-December—slightly above last year’s pace, but well behind the five preceding seasons. Adult flu vaccination coverage was also 42%, which is about in line with the prior two seasons.
State and local health officials are echoing the calls for broader vaccination. The New York State Department of Health said Friday it logged 4,546 flu hospitalizations during the week ended Dec. 27, the most it’s ever seen in a single week. That declaration came a week after it notched a record high number of flu cases. Multiple hospitals in New York are reportedly now requiring face masks for employees and visitors.
"We are having a more severe flu season than prior years, almost 1,000 more people were admitted to a hospital during this most recent seven-day period compared to the prior week," New York State Health Commissioner James McDonald, M.D., said Friday in a statement. "There is still time to get a flu shot, and remember, flu can be treated with antiviral medication if started within 48 hours of symptom onset, and your doctor deems [it] appropriate."
Of note, the escalating respiratory season comes as federal health authorities have pulled back on vaccine recommendations for young children, including the flu. Though nine children have reportedly died from influenza so far this season, last year’s 289 deaths, largely among unvaccinated children, was an all-time high since those data became widely reported in 2004.