Contact tracers are trying to determine if anyone caught COVID-19 during a boisterous St. Louis County Council meeting where many mask-less people spoke out against the county's new mask requirement.
The effort comes after someone at the meeting tested positive for COVID-19.
The delta variant of the coronavirus has prompted new mask mandates in St. Louis city and county, and one that began Monday in Kansas City.
The St. Louis County mandate was the subject of a turbulent, four-hour meeting last Tuesday.
Democratic County Executive Sam Page says many of those who spoke and attended ignored the mandate that requires masks in indoor public places.
