Most people in the United States live in areas where those who are healthy do not need to wear masks indoors, according to new US CDC guidance -- a radical change from what earlier Covid-19 metrics recommended.

Previously, CDC pointed to levels of coronavirus transmission within communities as a key metric for restrictions and recommended that people in areas with high or substantial levels of transmission -- about 99% of the population -- should wear masks indoors.

Now, the CDC's "Covid-19 community level" metrics are based on three pieces of data in a community: new Covid-19 hospitalizations, hospital capacity and new Covid-19 cases. Under the new recommendations, more than 70% of the US population is in a location with low or medium Covid-19 community levels. For those areas, there is no recommendation for indoor masking unless you are at potential "increased risk" for Covid-19 and if so, the CDC recommends talking to your doctor about wearing a mask.

Counties with fewer than 200 new Covid-19 cases per 100,000 people in the past week are considered to have "low" Covid-19 community levels if they have fewer than 10 new Covid-19 hospital admissions per 100,000 or less than 10% of staffed hospital beds occupied by Covid-19 patients on average in the past week.

Levels are "medium" if counties have 10 to nearly 20 new Covid-19 hospital admissions per 100,000 or between 10% and 14.9% of staffed hospital beds occupied by Covid-19 patients on average in the past week.

Levels are considered "high" if counties have 20 or more new Covid-19 hospital admissions per 100,000 or at least 15% of staffed hospital beds occupied by Covid-19 patients on average in the past week.

The update to CDC guidance comes when daily Covid-19 cases in the United States have fallen to a tenth of what they were at their peak last month, according to data from Johns Hopkins University. The 90% drop from an average of more than 802,000 cases per day on January 15 to less than 75,000 currently happened over six weeks.

In recent weeks, some states seem to have already made this shift in focus from community transmission to hospitalizations. Many states have made plans to lift indoor or school mask mandates based on their own metrics: declining hospitalization rates and having a larger share of fully vaccinated residents than the national average.