The flu virtually disappeared for two years as the pandemic raged. But the flu looks set to make a comeback this year in the US, threatening to cause a dreaded “twin-demic”.
While both the flu and the coronavirus are notoriously unpredictable, there’s a good chance COVID cases will resurface this winter, and there are worrying signs the flu could make a comeback, too.
“This could very well be the year we see a double pandemic,” says Dr. William Schaffner, professor of infectious diseases at Vanderbilt University. “That is, we have an increase in COVID and, simultaneously, an increase in influenza. We could have both affecting our population at the same time.”
The strongest indication that the flu could hit the US this winter is what happened during the southern hemisphere winter. The flu returned to some countries, such as Australia, where respiratory infection began to increase months earlier than normal and caused one of the worst flu seasons in recent years.
What happens in the southern hemisphere winter often foreshadows what will happen north of the equator.
“If we have a severe flu season, and if omicron variants continue to cause mostly mild illness, next winter could be a flu season much worse than COVID,” Schaffner warns.
And the combination of the two viruses could seriously affect the health system, he says. The Centers for Disease Control and Prevention Dear that the flu causes between 140,000 and 710,000 annual hospitalizations.
“We should be worried,” says Dr. richard webby, an infectious disease specialist at St. Jude Children’s Research Hospital. “I don’t necessarily think it’s a concern of running the hills. But we have to be concerned.”
The main reason the flu has basically disappeared in the last two years was because of behavioral changes people made to avoid COVID, such as staying home, avoiding public gatherings, wearing masks, and not traveling. That also prevented flu viruses from spreading. But those measures have mostly been abandoned.
“As community mitigation measures begin to be implemented around the world and people return to their normal activities, the flu has begun to circulate around the world,” says Dr. Alice Fry, who directs influenza epidemiology and prevention for CDC. “We can expect a flu season this year, for sure.”
Young children at especially high risk
the CDC is reporting that the flu is already starting to spread in parts of the South, like Texas. And experts warn that very young children may be at particular risk this year.
Although COVID-19 has generally been mild to the young, the flu often poses the greatest threat to both the elderly and children. The main strain of flu currently circulating, H3N2, tends to hit the elderly hard. But health experts are also concerned about young children who haven’t been exposed to the flu for two years.
“There are the 1-year-olds, the 2-year-olds and the 3-year-olds who are going to see it for the first time, and none of them have pre-existing immunity to influenza,” says Dr. helen chuassistant professor of medicine and allergy and infectious diseases and adjunct assistant professor of epidemiology at the University of Washington.
In fact, the flu seems to have hit young people in Australia particularly hard.
“We know that schools are really the places where influenza spreads. They really are considered the drivers of transmission,” says Chu. “It will be the spreaders. Then they will take it home to the parents. Then the parents will take it to the workplace. They will take it to the grandparents who are in a nursing home. And then those populations then get quite sick with the flu.” .
“I think we’re headed for a bad flu season,” says Chu.
‘Viral interference’ could outweigh the risks
Some experts doubt that COVID and the flu will reach the country simultaneously due to a phenomenon known as “viral interference,” which occurs when infection with one virus reduces the risk of contracting another. That’s another possible reason why the flu has disappeared in the last two years.
“It is possible that these two viruses will occur during the same season, but my intuition is that they will occur sequentially rather than both at the same time,” says Webby. “So I’m less worried about the double pandemic.”
However, Webby and others urge people to make sure everyone in the family gets a flu shot as soon as possible, especially if flu season comes early in the US as well (most years , officials don’t start pushing people to get a flu shot until October).
So far, it appears that this year’s flu shots are a good match with circulating strains and therefore should provide effective protection.
But health officials fear fewer people will be getting a flu shot this year than usual because of anti-vaccine sentiment that has surged in reaction to COVID shots. Flu vaccination rates they are already late.
“We’re concerned that people aren’t getting vaccinated. And the flu vaccine is the best prevention tool we have,” says the CDC’s Fry.
Fry also hopes that some of the habits people developed to fight COVID will continue and help mitigate the impact of the flu.
“The wild card here is that we don’t know how many mitigation practices people will use,” says Fry. “For example, people now stay home when they are sick instead of going to work. They keep their children out of school. Schools are strict about not letting children go to school if they are sick. All of these types of things could reduce transmission.”