Flu activity continues to dwindle nationwide, and although its patterns are hard to predict, experts say there has not been evidence to suggest influenza B will drive a second wave.
"It's not unusual to see an influenza B resurgence after the big A peak, but we've really seen no evidence of that so far," Michael Osterholm, PhD, director of the Center for Infectious Disease Research and Policy at the University of Minnesota in Minneapolis, told Becker's, adding that the Southern Hemisphere, which experts typically look at to predict U.S. flu patterns, did not see a rebound in influenza B.
Influenza A strains have driven the majority of cases since October, CDC data shows. Still, "whether activity will increase again just cannot be predicted," Alicia Budd, head of the CDC's domestic influenza surveillance team, said in a Feb. 16 email to Becker's.
Preliminary data from the CDC indicates the flu vaccine worked well this season. Data published Feb. 22 indicates the shots were 68 percent effective at preventing hospitalizations among children and 43 percent among adults overall. For adults 65 and older, protection against hospitalization fell to 35 percent. Flu vaccines are generally considered to have done well when effectiveness is between 40 percent and 60 percent.
So far this season, the CDC estimates there have been at least 25 million cases, 280,000 hospitalizations and 18,000 deaths. While the flu hit early, so far it has been an average flu year overall, Dr. Osterholm said. During surveillance weeks in November and December, hospitalizations hit rates at levels not seen that early in the season in more than a decade.
Even as the rates of flu, COVID-19 and respiratory syncytial virus have come down, hospitals continue to face significant capacity strain. Overall, hospitals are seeing greater volumes of high-acuity patients than they have in the past, coupled with labor shortages. In addition, workforce shortages across post-acute care facilities have been a key driver of capacity issues by limiting hospitals' ability to make timely discharges.