Thirteen children have died from the influenza virus this flu season, according to the latest statistics released from the Centers for Disease Control (CDC).

The latest CDC report noted that ten girls and three boys died of the flu as of December 29, and 24 states reported “widespread” activity.

This flu season has seen an increase in people seeking medical care for influenza-like illnesses, as outpatient health care provider visits in the U.S. increased to 4.1 percent, according to the data.

But the CDC says that part of the increase in visits for flu-like symptoms is due partly to “a reduction in routine healthcare visits during the winter holidays, as has occurred during previous seasons.”

In fact, more children died of the flu around the same time in 2017. Twenty-seven children died of the flu during the week ending December 29, according to the CDC.

The agency warned that “seasonal influenza activity continues to increase” and advised anyone six months or older who had not received their flu shots to get them from a health care provider.

“An annual flu vaccine is the best way to protect against influenza and its potentially serious complications,” the agency said in a statement. “Flu vaccination also has been shown to reduce severity of illness among people who get vaccinated but still get sick. For anyone 6 months or older who has not yet been vaccinated this season, CDC recommends that they get vaccinated now.”