The delta coronavirus variant is infecting a mounting number of people in rural Kansas and Missouri.

The variant, first detected in India in October, was upgraded by the Centers for Disease Control and Prevention this week from a "variant of interest" to a "variant of concern." The CDC estimates the delta variant accounts for about 10% of new cases in the U.S.

Missouri had the highest percentage of the delta variant at 6.8% of reported cases as of May 22, the latest CDC data.

Data from the CDC shows high community transmission in rural parts of Missouri and Kansas -- regions already struggling with slow vaccination rates.