71 of Minnesota's 87 counties have high or substantial community transmission of COVID

Nearly 40% of Minnesota has a "high" level of community transmission of COVID-19 — the worst possible categorization used by the Centers for Disease Control and Prevention (CDC).

Thirty-four counties now fall into the "high" transmission category, according to the latest data Wednesday afternoon from the CDC. That includes Hennepin and Anoka counties in the Twin Cities metro. Six days ago, just 14 counties had what the agency considers "high" levels of community transmission.

Meanwhile, an additional 37 counties have "substantial" levels of transmission.

That means in these 71 counties, the CDC recommends every individual wear a mask while in public indoor settings, regardless of whether or not they have been vaccinated. Sixty-four Minnesota counties were across this threshold one week ago.

Related: Number of MN counties with a 70% vaccination rate hasn't budged in weeks

Just one Minnesota county, Pipestone, has low transmission. The remaining 15 have moderate transmission.

The goal of the CDC's mask guidance in these hotspots is to slow the spread of the delta variant. While officials say the existing COVID-19 vaccines are effective at preventing people from getting seriously ill or dying due to the delta variant, data indicates vaccinated individuals can still spread the virus to others, endangering those who are not (or cannot be) vaccinated.

Related: MN's breakthrough infection statistics, including hospitalizations, deaths

Here are the Minnesota counties with high transmission, in alphabetical order:

1. Anoka County
2. Beltrami County
3. Chisago County
4. Clearwater County
5. Dodge County
6. Fillmore County
7. Freeborn County
8. Hennepin County
9. Houston County
10. Hubbard County
11. Itasca County
12. Jackson County
13. Kanabec County
14. Kandiyohi County
15. Le Sueur County
16. Lincoln County
17. Marshall County
18. McLeod County
19. Meeker County
20. Mower County
21. Nobles County
22. Norman County
23. Olmsted County
24. Otter Tail County
25. Pine County
26. Pope County
27. Rice County
28. Rock County
29. Sibley County
30. Stearns County
31. Steele County
32. Traverse County
33. Waseca County
34. Watonwan County

And here are the counties with substantial transmission:

1. Aitkin County
2. Becker County
3. Benton County
4. Blue Earth County
5. Carlton County
6. Carver County
7. Cass County
8. Cottonwood County
9. Crow Wing County
10. Dakota County
11. Douglas County
12. Faribault County
13. Goodhue County
14. Isanti County
15. Kittson County
16. Lyon County
17. Martin County
18. Mille Lacs County
19. Morrison County
20. Murray County
21. Nicollet County
22. Pennington County
23. Polk County
24. Ramsey County
25. Redwood County
26. Roseau County
27. Scott County
28. Sherburne County
29. St. Louis County
30. Stevens County
31. Todd County
32. Wabasha County
33. Wadena County
34. Washington County
35. Wilkin County
36. Winona County
37. Wright County

The classifications are based on one of two variables: Total new cases per 100,000 persons in the past seven days, and percentage of positive tests during the past seven days.