It seems children are likely spreading COVID-19 through youth sports and other extracurricular activities, according to the Centers for Disease Control and Prevention. Data shows after-school activities are creating clusters where the virus can spread among children—even more so than in the classroom.

"We know that these increases are due, in part, to more highly transmissible variants, which we are very closely monitoring," said Dr. Rochelle Walensky, CDC director, at the White House COVID-19 Response Team briefing earlier this week.

Indoor sports are particularly risky, according to public health experts. Playing sports like basketball, hockey and wrestling—especially without masks—has been causing an increase in cases in various parts of the U.S.

The CDC recommends children follow specific guidelines when engaging in sports and other activities, and limiting participation in certain activities.

"We're finding out that it's the team sports where kids are getting together, obviously many without masks, that are driving it — rather than in-the-classroom spread," Dr. Fauci told Good Morning America this week. "When you go back and take a look and try and track where these clusters of cases are coming from in the school, it's just that."

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In Florida and Minnesota, local health departments have traced outbreaks to youth sports. In Carver County, Minnesota, officials identified a cluster of children and adults infected with the faster-spreading B.1.1.7 variant that was traced back to school activities like hockey, wrestling, basketball, and skiing.

Public health officials in Carver County recommended that school and club team sports pause for two weeks, and urged kids in the county and nearby communities undergo COVID-19 testing and to wear masks when participating in school activities. A high school wrestling tournament was the cause of an outbreak in Florida during the winter, with 38 people testing positive.

Classrooms are not considered to be a driving force behind a rise in cases among children, with students, teachers, and staff all wearing masks while in classrooms across the U.S.

The B.1.1.7 variant of the novel coronavirus, which originated in the U.K., is now the dominant strain of the virus and approximately 50% more transmissible than other strains found in the U.S.

As for sports, health officials and the CDC recommend outdoor play as often as possible. Parents should stay in the loop about team protocol should a player test positive for COVID-19. The CDC has published guidance for youth sports teams during the pandemic, which includes over a dozen recommendations including minimizing the time spent indoors and reducing the amount of time players spend in close contact with each other.

Families should continue to mitigate risks when it comes to kids and sports to limit exposure and the potential spread of the virus.