February is usually the peak of flu season, with doctors’ offices and hospitals packed with suffering patients. But not this year.

Flu has virtually disappeared from the U.S., with reports coming in at far lower levels than anything seen in decades.

Experts say that measures put in place to fend off the coronavirus — mask wearing, social distancing and virtual schooling — were a big factor in preventing a “twindemic” of flu and COVID-19. A push to get more people vaccinated against flu probably helped, too, as did fewer people traveling, they say.

Another possible explanation: The coronavirus has essentially muscled aside flu and other bugs that are more common in the fall and winter. Scientists don’t fully understand the mechanism behind that, but it would be consistent with patterns seen when certain flu strains predominate over others, said Dr. Arnold Monto, a flu expert at the University of Michigan.

At the close of 2020, only 1.6% of visits to an outpatient provider in the nation were for symptoms of flu-like illness, according to the Center for Disease Control and Prevention’s FluView report. This was below the national baseline of 2.6%.

Only one pediatric flu death had been reported for the 2020-2021 flu season as of Feb. 13. The death was connected to Influenza B and occurred in November.

Though the national flu and pneumonia mortality rate was 13.6% — well above the epidemic threshold of 6.8% — the majority of these deaths have been attributed to COVID-19.

Forty-six states reported minimal flu activity at the end of 2020, while South Carolina and Nevada reported low activity. Mississippi reported moderate flue activity. For the week ending Feb. 13 — the most recent available CDC data — all states and districts reported minimal flu activity, with the exception of Texas, where insufficient data was collected.

Fewer than one in 100,000 people (0.6) had been hospitalized for the flu in the 2020-2021 season, compared to a rate 1.6 times higher (0.96) in 2011-2012, considered a low severity season.

 

The Associated Press contributed to this story.