(CNN) While they may be unpopular in some places, mask mandates work to slow the spread of Covid-19, according to new research published Friday by the US Centers for Disease Control and Prevention.
Since Covid-19 spreads predominantly through respiratory droplets, wearing a mask can protect others from the person wearing the mask who may have Covid-19. This month, the CDC released guidance that said masks can protect the wearer, too, by filtering incoming infectious droplets.
On July 2, as Covid-19 cases were surging in the state, Kansas Gov. Laura Kelly signed an executive order that made masks mandatory in public spaces. The majority of the state's counties, 81, opted out of this executive order, but 24 opted in or created their own mask mandate. The counties that did require masks account for two-thirds of Kansas' population.
The CDC and the Kansas Department of Health and Environment looked at the Covid-19 case trends between June 1 and July 2, before the mandate, and then July 3 to August 23, after the mandate, to compare what happened.
In the 24 counties that required people to wear masks in public, there was a net decrease of 6% in cases; whereas the disease continued to surge in the counties without the mandate. In those counties, the net increase in cases was 100%.
This research "adds to the evidence supporting the importance of wearing masks and implementing policies requiring their use to mitigate the spread of SARS-CoV-2," the report said.
This report is also consistent with other studies that have shown a decline in Covid-19 cases in 15 states and the District of Columbia, after mask mandates were put in place, compared with states that did not require masks and continued to see an increase in cases, the report said.
A CDC study in October in Arizona saw Covid-19 case numbers stabilize and then decrease after a mask mandate went into effect in June.
As of November 11, at least 35 states plus the District of Columbia and Puerto Rico have some type of mask requirement order in place statewide.
President-elect Joe Biden discussed a need for a national mask mandate Thursday with a bipartisan group of Republican and Democratic governors.
Wearing a mask, Biden said, is "not a political statement; it's a patriotic duty."
Some studies have shown that if there was a universal mask mandate, it could save thousands of lives.
As the number of Covid-19 cases has surged across the country, on Wednesday Kansas Gov. Kelly announced a new executive order that established another statewide face-covering protocol that takes effect November 25.
The new order allows local leaders a week to create and implement their own version of a mask ordinance that works for their communities.