Avian Flu Diary: CDC FluView Week 6: Season is Now Officially Ranked as High Severity

#18,618

After what appearing to have peaked in early January (see chart below), influenza resumed its upward trajectory in mid January, remains in extremely elevated for the second week running. Most cases are due to influenza A, with H1N1 edging out H3N2 55% to 44%.

The last time we saw this kind of flu activity was during the 2017/2018 flu season, which reached similar heights in week 5 of 2018 (see comparison below).

Key points from this week's FluView follow:

Weekly US Influenza Surveillance Report: Key Updates for Week 6, ending February 8, 2025

Key Points

Nationally, seasonal influenza activity remains elevated and is higher than or similar to the highest it has been all season for each indicator reported in FluView. In addition, the percent of specimens testing positive for influenza at clinical labs and the rate of laboratory confirmed influenza associated hospitalizations reported to FluSurvNet are higher than any peak week going back to the 2015-2016 and 2010-2011 seasons, respectively
Based on data available this week, this season is now classified as a high severity season overall and for all age groups (children, adults, older adults) for the first time since 2017-2018.
During Week 6, of the 4,214 viruses reported by public health laboratories, 4,079 were influenza A and 135 were influenza B. Of the 3,146 influenza A viruses subtyped during Week 6, 1,742 (55.4%) were influenza A(H1N1)pdm09, 1,404 (44.6%) were A(H3N2), and zero were A(H5).
One new avian influenza A(H5) case was reported to CDC this week. To date, human-to-human transmission of avian influenza A(H5) virus (H5 bird flu) has not been identified in the United States.
Outpatient respiratory illness is stable compared to last week but is higher than it has been all season and is above the baseline nationally for the eleventh consecutive week. All 10 HHS regions are above their region-specific baselines.
The week ending January 25, 2024, was the first time that the percent of deaths for influenza (1.7%) was higher than the percent of deaths for COVID-19. The percent of deaths for influenza has continued to increase and is 2.6% for the week ending February 8, 2025.
Eleven pediatric deaths associated with seasonal influenza virus infection were reported this week, bringing the 2024-2025 season total to 68 pediatric deaths.
CDC estimates that there have been at least 29 million illnesses, 370,000 hospitalizations, and 16,000 deaths from flu so far this season.
CDC recommends that everyone ages 6 months and older get an annual influenza (flu) vaccine.1
There are prescription flu antiviral drugs that can treat flu illness; those should be started as early as possible and are especially important for patients at higher risk for severe illness.2
Influenza viruses are among several viruses contributing to respiratory disease activity. CDC is providing updated, integrated information about COVID-19, flu, and respiratory syncytial virus (RSV) activity on a weekly basis.

It seems likely that there will be several more weeks of elevated influenza A activity ahead, and it is not uncommon to see a wave of Influenza B in the spring. With two Influenza A viruses co-circulating, even if you've already had the flu this year, you could still be vulnerable to the other strain.

All of which makes it still worth getting a flu shot if you haven't, and taking basic precautions (hand washing, wearing a mask in crowded indoor environment, staying home if sick, etc.).