The pattern in North America followed an extremely quiet flu season the Southern Hemisphere. The U.S. typically looks to countries like Australia for a glimpse at what might be coming to our shores. Doctors say they are beyond relieved that we didn’t see flu misery on top of the winter COVID-19 surge.
“The question is why, and the answer is pretty interesting,” Bogoch says.
First, he says, there are the precautions people have been taking for COVID, like masking, social distancing, and frequent hand-washing. Sure, not everybody is doing these things, but many are. “I don’t think we can ignore that,” he says.
Secondly, many people seem to have heeded public health advice to get a flu vaccine.
“At least in Canada, there was massive uptake of the flu vaccine this year,” Bogoch says.
Official numbers on vaccination rates for this year’s flu season aren’t yet available for the U.S., but so far, the CDC says nearly 194 million doses of flu vaccine have been distributed. That’s another record, topping last year’s distribution by about 20 million doses. Distribution isn’t the same as the number of shots going into arms, so it remains to be seen whether high vaccination coverage may have played an important role in tamping down the flu here.
Bogoch also points to less international travel as a reason the flu wasn’t a big deal.
“This is an infection that that follows mobility patterns as well,” he says, “and there’s just remarkably less human mobility this year.”
Perhaps the biggest reason for the disappearance of the flu this year has to do with children.
“Children are the great distributors of the influenza virus in our society,” Schaffner says.
Kids shed flu virus for longer than adults do, and they shed it a day or two before they show any symptoms, says Jennifer Nayak, MD, a pediatric infectious disease specialist at the University of Rochester Medical School. She has studied the life cycle of flu infections in children.
“As we’ve learned the hard way, with COVID, shedding virus before you are symptomatic makes it really, really hard to contain an infection,” she says.