As summer faded into fall, public health officials started sounding the alarm: If this flu season were anything like previous ones, hospitals overwhelmed by COVID-19 patients could, without drastic intervention, face a catastrophic influx of illnesses.
That intervention primarily focused on containing the coronavirus through a range of restrictions and advisories. Governor Charlie Baker also issued a first-in-the-nation mandate requiring flu vaccines for almost all students under age 30.
“The more people who get the flu shot don’t get the flu and don’t wind up in the ER,” Baker said in August.
And while coronavirus cases have skyrocketed, the “twindemic” has so far been averted. Cases of influenza are low, both in Massachusetts and nationally.
The success in limiting the flu spread is likely due to a combination of factors, specialists said. While it’s hard to be certain, the steps people have taken to lower their risk of contracting the coronavirus are likely helping them avoid the flu as well, said Dr. Benjamin Linas, an associate professor of epidemiology at the Boston University School of Medicine. The public health emphasis on flu vaccines also has likely contributed.
“Everything that we’re doing for COVID should also help us with the flu,” he said. “If we can completely change the shape of the flu curve, I think we can really credit COVID mitigation for that.”
Influenza and COVID-19 are both upper respiratory viruses, transmitted in about the same way. That means an infected person wearing a mask over the nose and mouth can lower the risk of spreading the virus to others. Physical distancing and extra awareness of hand-washing and sanitizing can lower that risk as well.
“It’s a big help right now,” Linas said. “Our hospitals are being taxed, and to the extent that they’re also not being taxed by influenza, that’s helpful.”
Health officials also suspect that the dearth of international travel helped tamp down the flu this year, as the virus usually travels around the planet from one winter to another.
That means flu-like symptoms — high fever, coughing, fatigue, and the like — are more likely to be COVID-19 this year, said Dr. David Hooper, chief of the Infection Control Unit and associate chief of the Division of Infectious Diseases at Massachusetts General Hospital.
People experiencing those symptoms should quarantine and get tested. Some labs may be able to test a single sample for both the coronavirus and the flu, Hooper said.
From fall 2019 to spring 2020, the Centers for Disease Control estimated that influenza was likely associated with 38 million illnesses, 18 million medical visits, 405,000 hospitalizations, and about 22,000 deaths.
During the last week of 2020, the CDC tested more than 25,000 samples for influenza. Just 74 — 0.3 percent — came back positive.
In Massachusetts, the Department of Public Health classified flu risk as minimal during the last week of December. Just 1.1 percent of visits to health care providers were for possible flu, according to the department’s statistics. That’s significantly lower than the 2.5 percent of visits in the last week of 2019, which was roughly on par with the two previous years.
In future years, when COVID-19 cases are less common, the methods used to keep the pandemic under control also can be effective against the flu, Hooper said. He pointed to countries like Japan, where mask-wearing during flu season is more common. But whether Americans are willing to keep masking up in the fall and winter remains to be seen.
“I suspect there will be little appetite for doing the masking routinely” in public settings, he said, though hospitals will likely maintain more stringent protocols. “There is eagerness to get back to pre-COVID times, when we didn’t do that routinely.”
Still, the post-pandemic future might have people getting an annual flu shot and an annual coronavirus vaccine.
“Influenza’s been around, well, for a long, long time,” Hooper said. “It’s not going to go away. And the general feeling is that SARS-CoV-2 is not going to go away, either.”
Gal Tziperman Lotan is a former Globe staff member.