This past summer, public health officials sounded warnings about the dangers of an impending flu epidemic on top of the coronavirus pandemic.
Yet this year's flu season has been exceptionally mild.
During the 2019-2020 flu season, some 400,000 people were hospitalized for the flu, with 22,000 deaths, according to the Centers for Disease Control and Prevention. Last week — just ahead of the season's usual peak — the CDC had recorded just 165 flu-related hospitalizations since October.
"Flu has been essentially nonexistent," Dr. William Schaffner, infectious disease specialist at Vanderbilt University, said in an interview with Weekend Edition.
The mild season has benefitted from measures like masks and social distancing, he said. It helps too that, last year, a record number of people got a flu shot.
But Schaffner says there's more to it: Kids — habitual superspreaders — are staying home.
"Children are generally thought of as having the distribution franchise for the influenza virus," Schaffner said. "They produce much more virus, they shed more virus for longer periods of time."
But over the course of the coronavirus pandemic, as schools went virtual and children interacted less, the chances of spreading the flu narrowed.
For Schaffner, the result highlights a distinction in the nature of transmission among the respiratory viruses.
"COVID can be transmitted very readily among adults — very contagious — but flu, I think, really needs children to spread it around amongst themselves and then seed, if you will, the adults in their home and their neighbors," he said.
Since so many dodged the flu this season, Schaffner warns that the virus could hit people harder than normal this fall — when health professionals predict the country will get closer to normalcy.
"Many of us didn't get a boost from encountering the flu virus this year, and so we haven't had a chance to build up our antibodies," he said. "All the more important to get vaccinated this fall."
Samantha Balaban, Ed McNulty and Martha Ann Overland produced and edited the audio version of this story.
LULU GARCIA-NAVARRO, HOST:
It is flu season, and it wasn't that long ago that public health officials were warning about the danger of a flu epidemic on top of the coronavirus pandemic. But we have been wearing masks and keeping socially distant, and a record number of people got a flu shot. We'll turn now to Dr. William Schaffner - he's an infectious disease specialist at Vanderbilt University - for a flu season update.
Dr. Schaffner, thanks for being with us.
WILLIAM SCHAFFNER: Good to be with you, always.
GARCIA-NAVARRO: I want to begin with a moment from some other reporting I did for this weekend. I was at the pediatric intensive care unit at a local hospital, and Dr. Michael Bell of Children's National told me this.
MICHAEL BELL: Usually this time of year, we have dozens of kids with cold viruses that are sick with us. And this year - absolutely nobody. It's bizarre.
GARCIA-NAVARRO: And the numbers bear that out. Last year, the CDC counted some 405,000 hospitalizations for the flu in the United States. So far this season - 165. That's not a mistake - not thousand, just 165. Can that all really be from social distancing?
SCHAFFNER: Well, I think social distancing is important, of course. But you're right. Flu has been essentially nonexistent. The major issue, of course, is that children generally are thought of as having the distribution franchise for the influenza virus. They produce much more virus. They shed more virus for longer periods of time. And so they spread it amongst themselves, and then they bring it home to mom and dad, Aunt Susie (ph) and Grandpa Tom (ph). Well, children haven't been getting together. They've been going to school virtually. They haven't been playing together.
SCHAFFNER: And of all the reasons, I think that's the major reason we've had such a low flu season.
GARCIA-NAVARRO: I'm also wondering, though, because people also haven't been in offices, you know, where I can attest I have gotten sick before.
SCHAFFNER: Of course. We haven't traveled - we adults, that is. We haven't gone into offices. We're wearing masks. We're observing social distancing, not going to large groups. So the transmission among adults, also the opportunities for transmission, have been profoundly reduced. But I don't think that's the major issue because you see COVID's been transmitted among adults. And so how is it that we haven't had flu? And I think the critical issue is the children.
GARCIA-NAVARRO: I had heard some doctors speculate - and this is really speculation - that there might be something with COVID-19 itself or the coronavirus that blocks the flu virus from proliferating inside a host.
SCHAFFNER: Speculation - but I haven't seen anything scientifically to promote that - to support that, I should say. So I think this shows us that viruses, even respiratory viruses, are not the same. COVID can be transmitted very readily among adults - very contagious. But flu, I think, really needs children to spread it around amongst themselves and then seed, if you will, the adults in their home and their neighbors.
GARCIA-NAVARRO: I imagine there's a lot of investigation into this right now. What do you think the big takeaway is, though, for a flu specialist like yourself in order to save lives when the coronavirus pandemic is over?
SCHAFFNER: I think the important thing is, remember, fall will be coming this year. Get your flu shot because we'll be back amongst ourselves, providing opportunities for that virus to spread. And it also makes people very sick, sends them to the hospital and kills them, I'm afraid. Many of us didn't get a boost from encountering the flu virus this year, and so we haven't had a chance to build up our antibodies. All the more important to get vaccinated this fall.
GARCIA-NAVARRO: Dr. William Schaffner is a professor of medicine at Vanderbilt University and a very clear explainer of issues to do with the flu.
Thank you very much.
SCHAFFNER: My pleasure. Transcript provided by NPR, Copyright NPR.