Flu activity is still fairly high in some parts of the United States, and the number of patients hospitalized with the flu has been increasing over the past week, according to CDC data.
Flu season continues in May
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 between 6.7 and 11 million flu illnesses, between 69,000 and 140,000 flu hospitalizations, and 4,200 to 13,000 flu deaths this season, including 24 pediatric flu deaths.
For the week ending in May 14, 4,418 positive influenza tests were reported to CDC by clinical laboratories, down from 6,330 the week before.
Meanwhile, influenza hospitalizations increased slightly, with 3,153 lab-confirmed flu cases admitted to a hospital, up from 3,071 the week before.
For the week ending in May 14, Colorado, the District of Columbia, Maine, Massachusetts, New Jersey, New York, and Rhode Island all reported moderate flu activity. Florida, New Mexico, and Puerto Rico reported high levels of flu activity. No states reported very high levels of flu activity.
Meanwhile, for the week ending in May 14, the percentage of visits to an outpatient provider for respiratory illness was 2.4%, below the national baseline of 2.5%, and 0.7% of long-term care facilities reported at least one positive flu test among its residents, roughly the same as the week before.
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 test rates within the UNM Health Sciences system have been around 4%, but positive flu tests have increased to 17%.
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.
"We really want to start them on the correct treatment as soon as possible," she said (Carbajal, Becker's Hospital Review, 5/20; CDC Weekly U.S. Influenza Surveillance Report, 5/20; CDC 2021-2022 Preliminary In-Season Burden Estimate, 5/20)