The United States is in the midst of a late-season flu spike, according to data from the Centers for Disease Control and Prevention, with nearly one in 10 positive tests reported at the peak in mid-April.
But even with that spike, an NBC News analysis of 7-year CDC data shows this year’s flu season is still well below pre-pandemic levels.
“We’re late,” said Dr. Carrie Horn, chief medical officer at National Jewish Health in Denver. “But they’re not so high that we say there’s a flu epidemic.”
It will be the first time since 1982 that such an increase has occurred so late in the typical flu season, said Lynnette Brammer, head of the CDC’s National Influenza Surveillance Team.
“We don’t usually think of the flu in May, but it’s definitely still there,” Brammer said, adding that it’s possible rates will rise further this season.
Although this season had far fewer cases than previous seasons, the late-season spike brought positivity rates closer to what they would be at the end of a typical flu season.
So far this season, the CDC reported, there have been at least 5.7 million cases of the flu and about 59,000 hospitalizations. About 3,600 people died, including 24 children.
Respiratory illnesses are increasing in New Mexico and Colorado in particular, according to the CDC’s latest flu data.
Doctors there say patients arrive with fever, cough, body aches – which could signal the flu, Covid-19 or a number of other respiratory viruses.
“Almost every day I see at least one person with a case of something that we need to address,” said Dr. Melissa Martinez, professor of internal medicine at New Mexico University of Health Sciences.
But it is the flu that turns out to be the cause of a number of current respiratory illnesses, Martinez said. In recent weeks, the proportion of positive Covid tests within UNM’s health sciences system has hovered around 4%, she said, while the proportion of positive flu tests is reaching 17%.
The timing of flu cases is unusual, Martinez said. “To see an upsurge in the flu this late in the season is really strange.”
The flu is usually spread through respiratory droplets when a person sneezes, coughs or even talks. The rise coincided as Covid-19 masking largely fell to a nationwide minimum.
Despite the increase in flu cases, Martinez said, the total number of flu cases is low compared to previous seasons.
“It’s a drop in the ocean compared to what we’ve seen in other years,” she said.
While the current season’s test positivity rate has yet to exceed 10%, previous seasons in the recent past have peaked at over 30%.
The dominant strain this year has been H3N2, which experts say tends to be more virulent and often causes more severe disease.
Because cases peak so late in the season, there’s still time to get a flu shot, Brammer said, even if the vaccine doesn’t quite match the current strain circulating.
Testing to determine the cause of a respiratory illness — whether flu or Covid — is critical, Martinez said. Antiviral treatments specific to both viruses are available, but they work best when given early in the disease.
“We really want to get them the right treatment as soon as possible,” she said.
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