AUSTIN, Texas (CBSDFW.COM) – The rate of positive virus cases in Texas has soared to the highest levels of the pandemic and state health officials are not yet able to fully explain why.

The infection rate in Texas was at a seven-day average of more than 24% on Thursday, meaning that nearly 1 in every 4 coronavirus tests were coming back positive.

The spike comes as thousands of Texas schools are reopening this week.

Gov. Greg Abbott says state health officials have brought in a data team to look into recent trends.

Testing has dramatically dropped off in Texas, where the daily testing average has fallen to half of levels seen in July.

Officials say testing supply isn’t the problem.

Dallas County officials say testing demand has dropped by 40%.

Health experts worry that long lines for testing earlier this summer and even longer waits for results may be discouraging people without symptoms from even bothering.

The high infection rate threatens to further drag out Texas bars staying shut. Abbott says the number needs to be below 10% before the state can consider reopening bars, which have been closed since June.

(© Copyright 2020 CBS Broadcasting Inc. All Rights Reserved. The Associated Press contributed to this report.)