Des Moines RegisterView CommentsPolk County late last week was among the 10 counties in the United States where the coronavirus was spreading fastest, a Des Moines Register analysis of national COVID-19 data confirmed.An unreleased White House coronavirus task force report  on Monday listed 10 counties where coronavirus had spread the fastest in the week before May 7, the date of the report. Polk County, the core of the Des Moines metro area, was No. 8 on that list.Dallas County, also part of the metro area, had nearly as much growth, and was just outside the top...…Des Moines RegisterView CommentsPolk County late last week was among the 10 counties in the United States where the coronavirus was spreading fastest, a Des Moines Register analysis of national COVID-19 data confirmed.An unreleased White House coronavirus task force report  on Monday listed 10 counties where coronavirus had spread the fastest in the week before May 7, the date of the report. Polk County, the core of the Des Moines metro area, was No. 8 on that list.Dallas County, also part of the metro area, had nearly as much growth, and was just outside the top...WW…