The United States is currently seeing an increase in flu cases—something that hasn't happened this late in the flu season since 1982. However, overall the number of flu cases have been "a drop in the bucket" compared with pre-pandemic seasons.
A late-season rise in flu cases
Typically, flu season begins in October and peaks between December and February. However, CDC data shows that the United States is currently experiencing a late-season increase in flu cases, with the flu positivity test rate reaching almost 10% in mid-April.
According to Lynnette Brammer, head of CDC's domestic influenza surveillance team, an increase this late in the flu season has not been observed in decades. "We aren't used to thinking of flu in May, but it's definitely still out there," she said, adding that rates could continue to rise in the coming weeks.
So far, CDC estimates that there have been at 5.7 million cases of flu, 59,000 hospitalizations, and 3,600 deaths, including 24 children, this flu season. Right now, data suggests that flu cases are increasing in New Mexico and Colorado in particular.
Melissa Martinez, a professor of internal medicine at University of New Mexico (UNM) Health Sciences, said the flu is behind a good proportion of the respiratory viruses currently circulating in her area. Over the past few weeks, positive Covid-19 tests within the UNM Health Sciences system has been around 4%, but positive flu tests have increased to 17%.
However, even with the late-season increase in cases, levels of the flu still remain far below pre-pandemic levels, according to an NBC News analysis of CDC flu data over the last seven years. Currently, the test positivity rate this season has not exceeded 10%. In comparison, past flu seasons have usually seen their test positivity rates peak at over 30%.
Overall, the number of flu cases this season is "a drop in the bucket compared to what we've seen in other years," Martinez said.
According to Brammer, with cases spreading so late in the flu season, people still have time to get a flu shot. This year's dominant flu strain, H3N2, is more virulent and can cause more severe illness, experts say. And even though this year's flu vaccine is not as effective against H3N2, CDC still recommends Americans get vaccinated since it could "prevent serious outcomes."
In addition, Martinez said antiviral treatments for the flu are available, but they are most effective when patients receive them soon after developing symptoms.