NEW YORK— The U.S. winter virus season is in full force, and by one measure is the most intense in 15 years.

One indicator of flu activity is the percentage of doctor’s office visits driven by flu-like symptoms. Last week, that number was clearly higher than the peak of any winter flu season since 2009-2010, when a swine flu pandemic hit the nation, according to data posted Friday morning by the Centers for Disease Control and Prevention.

Of course, other viral infections can be mistaken for flu. But COVID-19 appears to be on the decline, according to hospital data and to CDC modeling projections. Available data also suggests another respiratory illness, RSV, has been fading nationally.

The flu has forced schools to shut down in some states. The Godley Independent School District, a 3,200-student system near Fort Worth, Texas, last week closed for three days after 650 students and 60 staff were out Tuesday.

Jeff Meador, a district spokesman, said the vast majority of illnesses there have been flu, plus some strep throat.

— The Associated Press