As the number of COVID-19 cases climb in most states, the Centers for Disease Control and Prevention says it has discovered a pattern in young adults.

The percentage of positive test results start going up among those under age 25 about a month before a county is designated a coronavirus hot spot.

Dr. Deborah Brix, a White House Coronavirus Task Force member, says the amount of asymptomatic spread is large.

"When you start to look at this college data, it may be up to 80% of individuals under 30 are asymptomatic and we're still getting the data from all of the colleges," Birx said.

CDC researchers say understanding and tracking positive test rates by age group could help public health officials identify future hot spots and better prevent and prepare for a rise in COVID-19 cases.

Birx says it's also important to identify those who are asymptomatic.

As temperatures get cooler, Birx urges everyone to keep their masks on -- and their guards up.