How serious will the flu be? Here’s what you need to know after last year’s record-breaking season
After a difficult and record-breaking flu season, doctors and health officials are bracing for a new wave of fever, misery and respiratory distress.
In the UK, health authorities are warning of an early rise in flu levels among children and young adults. In Japan, health authorities recently declared a flu epidemic and closed schools after recording an unusually high number of flu cases early in the season.
What does this mean for the United States?
Typically, cases of influenza begin to increase in November, along with RSV (respiratory syncytial virus) and enteroviruses, and peak in February. But the chaos of job cuts at the Centers for Disease Control and Prevention and the government shutdown could make it difficult to know how the virus is unfolding this fall, experts worry.
The CDC’s last report on flu in the United States was for the week ending September 20, when activity was minimal.
Angela Rasmussen, a virologist at the University of Saskatchewan, worries about the possibility of limited flu surveillance by the CDC, leaving the United States blind to the size and scope of flu outbreaks.
“Everything from awareness campaigns to additional logistical efforts to actually distribute the vaccines” could be affected, Rasmussen said. “This information may simply not be available, so it will be very difficult to coordinate a national response,” she said.
Last year’s flu was tough. There have been about 1.1 million flu-related hospitalizations, the highest rate in 14 years, according to the CDC. And there were the highest number of doctor visits for flu-like illnesses in more than a decade.
An estimated 38,000 to 99,000 deaths have been associated with the 2024-2025 flu season, according to a preliminary assessment from the CDC. For children, it was one of the deadliest years on record: 280 children died from the flu. At least three of these children died in June and July, well outside the typical flu season.
How serious will the flu be?
The flu is notoriously difficult to predict, and this year things already look a little different.
The CDC predicted in late August that this flu season would be milder than last year. However, it’s possible that certain age groups could be hit hard, especially if people don’t get the flu vaccine.
The main strains of flu currently in circulation are similar to those which caused the serious epidemics of last season: H1N1 and H3N2 for influenza A, as well as for influenza B.
“It’s a little early to know which strains will predominate this year during flu season, but there is certainly a risk that similar highly virulent strains will circulate again this year,” said Dr. George Diaz, a member of the Infectious Diseases Society of America and chief of medicine at Providence Regional Medical Center in Everett, Washington. “This prediction of a moderate season could be wrong, and it could be another severe flu season,” he said.
“We’re still very early in the flu season in North America, and it’s a little difficult to know for sure,” he added.
Even if someone got the flu last year, they will still be vulnerable to the new version because immunity wanes over time, especially in older adults and immunocompromised people, experts say.
When is the best time to get your flu vaccine?
Tension is just one factor in the severity of the situation this year. Vaccine hesitancy and weakening public health infrastructure in the United States could contribute to the spread of influenza.
“This will largely be driven more by social and political changes than by changes related to virology,” Rasmussen said.
Last flu season, fewer than half of children were vaccinated against the flu, a drop of more than 20 percentage points from the 2019-2020 season. This year, that trend is expected to continue, Rasmussen said.
Dr. William Schaffner, a professor of infectious diseases at Vanderbilt University Medical Center, said it’s difficult to know how serious the situation will be this year in the United States, but that it is very unusual to have “two ultra-severe seasons in a row.”
So even though the virus hasn’t changed much, getting vaccinated is still the best way to protect yourself against the worst of the season.
“October is the ideal time to get vaccinated,” he said. “This should provide quite reasonable protection throughout what we consider to be the flu season, through February and March.”
