Here’s a fresh wake-up call for those struggling with “pandemic fatigue.”

Hospitals are seeing a rising number of adult patients in their 30s and 40 coming down with severe COVID-19 symptoms. According to the head of the CDC, it’s due to the spread of new variant strains of the virus that experts fear are more transmittable and potentially more lethal.

The B.1.1.7 variant from the United Kingdom is highly contagious and has, according to Dr. Walensky, become the dominant strain in the U.S. Cases connected to the B.1.1.7 variant now number 16,000 across the country.

This comes as the CDC is warning parents that youth sports may be spreading COVID-19 through activities such as wrestling, soccer, basketball and hockey. Those sports and other after school activities, Dr. Walensky says, “are creating clusters where coronavirus can spread among children.”

She blames the highly transmittable variant strains for helping the virus spread among children.

Parents are urged to follow the CDC’s recommended guidelines for youth sport participation. The organization listed nearly a dozen different recommendations, including minimizing the time spent indoors and reducing the amount of time players spend in close contact with each other.