Health officials say two factors might signal a severe flu season is in store for the U.S.: outbreaks at college campuses and a dominant strain associated with particularly bad flu seasons, NBC News reported Nov. 19.
At the University of Michigan in Ann Arbor, at least 528 students have contracted the flu since Oct. 6 and CDC officials are investigating the outbreak. The campus's flu positivity rate is 37 percent, compared with the country's 0.3 percent flu positivity rate. About 77 percent of cases at the university so far have been in unvaccinated students.
Flu outbreaks are hitting other college campuses as well, including the University of Florida in Gainesville and the University of Rhode Island in South Kingstown, NBC reports.
Overall influenza activity is still low in the U.S., though more than 90 percent of flu cases so far this year are the H3N2 strain, CDC data shows. The strain is associated with more severe flu seasons, health officials said.
“The majority of the time flu infection is going to be uncomplicated — you’re not going to feel well," said Alex Ho, MD, medical director of emergency services at Tallahassee (Fla.) Memorial Healthcare. "But what we’ve seen is, during years when H3N2 is circulating, we’ve had higher rates of hospitalization and death," he told the news outlet.
During the 2017-19 flu season, the H3N2 was the dominant strain. During that time, 710,000 flu-related hospitalizations and 52,000 flu-related deaths occurred in the U.S. — the worst since the 2009 H1N1 pandemic, NBC reports.
Health officials emphasized it's still early in the flu season, with time for the dominant strain to change.
"While the predominant strain we’re seeing is H3N2 right now, it may not be for the entire season," Alicia Budd, an epidemiologist at the CDC's influenza division, told NBC. "The flu does unusual things all the time and we’ve seen situations where early-season outbreaks are not indicative of the strain that prevails for the season."