Unusually late flu season

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Colorado has experienced a strange, spring spike in flu cases this year, and like many other trends in the post-pandemic world, this year’s odd flu season likely is related to COVID-19.

“It’s wild. It’s throwing everyone for a loop,” infectious disease expert, Dr. Michelle Barron, said of the 2022 flu season. “A lot of people have caught the flu in the last few weeks. It’s here. A lot of us got our flu shots in August. The vaccine might not have been a perfect match for this year’s flu. And any protection we had probably has worn off by now.”

Flu cases jumped in April and May at the same time that Colorado has experienced a new wave of COVID-19 cases. You could call the convergence of flu and COVID-19 infections a “twindemic” of sorts.

“It’s the weirdest flu season I’ve ever seen,” said Barron, who is senior medical director of infection prevention and control at UCHealth University of Colorado Hospital on the Anschutz Medical Campus.

Along with the spread of flu and COVID-19, many people are experiencing seasonal allergies as spring plants bloom. Those who are feeling sniffly or achy can’t be sure what’s making them sick unless they get tested for COVID-19 and the flu.

Typically, flu cases in North America peak during the winter months from December through February. This year, in Colorado’s most populous counties, flu cases began to climb in December, then dipped to uncharacteristically low levels in January and February. They then began to inch up again in March, and during April and May reached very high levels.

Barron sees a direct link between the end of COVID-19 mask mandates and the spring spike in flu infections.

“It has everything to do with COVID-19,” said Barron

“In February and March, when people stopped wearing masks, we started seeing flu cases rise. By April and May, there were more than 1,100 cases a week (in Colorado’s most populous counties),” Barron said.

On top of people not wearing masks in the spring, protection from fall flu shots also was decreasing

The CDC has extended its usual flu-season reporting because there is still so much flu activity going on. CDC data shows that after an initial peak, flu cases went down in mid-December and January, but picked back up during the first of the year.

Norton Healthcare nurse practitioner Trisha Walton says while she was working in urgent care in April, she saw more flu than COVID-19 cases.

Now, she’s at Norton’s new Community Medical Associates Springhurst office, and she’s urging patients to continue to be vigilant with handwashing and hygiene.

She says while the medical community has noticed an uptick in flu cases, at least some of that could have to do with testing.

Walton says anyone who’s feeling symptoms should stay home and quarantine for a full 24 hours after becoming fever-free.

I hope you all get through this without any complications.

The 2021-2022 flu season was the longest one on record in the United States, officials said, but it was also one of the most mild.

Influenza activity began to increase in November and remained elevated through mid-June, according to a report recently released from the Centers for Disease Control and Prevention.

In New York State, there were two peaks in lab-confirmed flu cases, one in December and the second in April.

The report notes that flu season usually peaks in February and drops off in the spring, with surveillance ending around May. This year, the Health Department said it would extend the flu surveillance period beyond May because of persistent elevated flu activity. Experts said it’s not clear if the unusual flu season pattern is somehow linked to the COVID-19 pandemic.

“Quite frankly, it’s a little odd,” said Dr. Bruce Farber, chief of public health and epidemiology for Northwell Health. “The flu season was expected to be long and difficult after the 2020-2021 flu season was so mild.”

Nationally, the CDC estimates that this year’s influenza virus infection resulted in between 8 million and 13 million symptomatic illnesses, 3.7 million to 6.1 million medical visits, 82,000 to 170,000 hospitalizations, and 5,000 to 14,000 deaths in the U.S. The agency said those are lower than estimates for any of the 10 influenza seasons preceding the pandemic.

Farber pointed out that the flu virtually disappeared in 2020-2021 as a result of masking, social distancing and other safety precautions taken due to the pandemic.

While flu did not come back in a particularly virulent way, meaning the illnesses were relatively mild, it was prolonged.

Farber said doctors are also seeing more cases of respiratory illnesses, such as respiratory syncytial virus (RSV), which usually appear in the winter.

“It’s hard for me to think that there's not some relationship that we've not been smart enough to understand yet,” Farber said, about any correlation between the COVID-19 pandemic and the unusual flu season. “We do know that people who got COVID at least made some antibodies against other coronaviruses so certain common colds, those caused by coronavirus, not obviously COVID, were potentially less common in the setting of COVID epidemic, but that would not apply to flu and RSV.”

Farber also pointed out that some people make antibodies after a respiratory illness that could give them some level of immunity against other respiratory illnesses for a relatively short period of time.

In addition, fewer adults across the U.S. got the flu shots this year, CDC statistics show. About 34.7% of adults between the ages of 18-49 received their vaccination. It was about 50% for adults between the ages of 50 to 64 years and 67.7% for adults 65 years and older. About 55.3% of children under the age of 18 received flu shots as of April 2022.