Avian Flu Diary: CDC FluView Week 13: Late Season influenza Activity Continues to Increase

#16,680

After peaking in late December, the first real flu season since the start of the COVID pandemic began to decline quickly, bottoming out in mid-February (see chart above). Since then, we've see a slow, but steady, increase in flu activity around the nation, albeit still below the national baseline.

Most of this increased flu activity has been reported from the central and south central states, but this week we are seeing increased activity in New England as well.

The key points from this week's FluView include:

Key Points
Influenza activity increased nationally this week. Influenza activity is highest in the central and south-central regions of the country and is increasing in the northeastern regions.
The majority of influenza viruses detected are A(H3N2). H3N2 viruses identified so far this season are genetically closely related to the vaccine virus. Antigenic data show that the majority of the H3N2 viruses characterized are antigenically different from the vaccine reference viruses. While the number of B/Victoria viruses circulating this season is small, the majority of the B/Victoria viruses characterized are antigenically similar to the vaccine reference virus.
The percentage of outpatient visits due to respiratory illness increased slightly this week compared with last week and remains below baseline. Influenza is contributing to levels of respiratory illness, but other respiratory viruses are also circulating. The relative contribution of influenza varies by location.
The number of hospital admissions reported to HHS Protect has increased each week for the past nine weeks.
The cumulative hospitalization rate in the FluSurv-NET system is higher than the rate for the entire 2020-2021 season, but lower than the rate seen at this time during the four seasons preceding the COVID-19 pandemic.
Two influenza-associated pediatric deaths were reported this week. There have been 16 pediatric deaths reported this season.
CDC estimates that, so far this season, there have been at least 3.8 million flu illnesses, 38,000 hospitalizations, and 2,300 deaths from flu.
An annual flu vaccine is the best way to protect against flu. Vaccination can prevent serious outcomes in people who get vaccinated but still get sick. CDC continues to recommend that everyone ages 6 months and older get a flu vaccine as long as flu activity continues.
Flu vaccines are available at many different locations, including pharmacies and health departments. Visit www.vaccines.gov to find a flu vaccine near you.
There are also flu antiviral drugs that can be used to treat flu illness.

After two years of COVID mitigation (face masks, social distancing, etc.) community levels of influenza immunity are believed to be low, and with more and more people skipping face masks, and more social intermingling, the potential for seeing `out-of-season' respiratory outbreaks is higher than usual.

Two weeks ago, in The Lancet: SARS-CoV-2 Co-infection With Influenza Viruses, RSV, or Adenoviruses we saw evidence that coinfection among hospitalized patients is linked to a four-fold increased risk of requiring mechanical ventilation, and a roughly doubled risk for death.

With the rise of the BA.2 variant and some indications that COVID activity is once again starting to increase, the next few months may not be as free from viral threats as many would have hoped.