One of the areas of concern Abbott mentioned was Hays County, where 476 of the 938 confirmed cases are people ages 20 to 29. People in their 20s accounted for 50.7% of all the cases in Hays County as of Monday, an increase from Friday, when the age group made up 42% of total cases.
https://www.texastribune.org/2020/06/16/texas-coronavirus-spike-young-adults/
https://www.texastribune.org/2020/06/16/texas-coronavirus-spike-young-adults/