Photo: Chip Somodevilla/Getty Images

Some states' requirements that face masks be worn in public may have led to hundreds of thousands of fewer coronavirus cases than there would have been without the mandates, according to a new study in Health Affairs.

Yes, but: Despite the growing body of evidence that this simple mitigation strategy is one of our best defenses against the coronavirus, wearing them remains controversial, and mandating their use even more so.

Between the lines: When everyone wears a face mask, it helps reduce spread of the virus by all carriers — including those who are asymptomatic and pre-symptomatic.

  • The study found a "significant decline in daily COVID-19 growth rate after mandating facial covers in public, with the effect increasing over time after signing the order."
  • Although only 15 states plus the District of Columbia required mask use in public, between 230,000 and 450,000 coronavirus cases may have been averted by May 22.
  • 20 other states have more limited mask requirements, but "results indicate no evidence of declines in daily COVID-19 growth rates with the employee-only mandates," the authors write.

Go deeper: The rise of the designer face mask

Go deeper

Where the science stands on using face masks against coronavirus

Illustration: Sarah Grillo/Axios

Scientific evidence shows face masks can help to control the spread of the novel coronavirus, but the nuances and changes in messaging about their use are complicating public health efforts.

Why it matters: COVID-19 cases are rising in many parts of the U.S., but politics, distrust in public health advice and science are coming to a head over face masks.

Updated Jun 30, 2020 - Health

Kansas becomes latest state to make wearing masks in public mandatory

Kansas Gov. Laura Kelly. Photo: Mark Reinstein/Corbis via Getty Images

Gov. Laura Kelly (D) announced in a statement on Monday that people in Kansas will be required to wear face masks while in public due to the coronavirus pandemic.

Driving the news: The order, effective this Friday, comes as several states are seeing spikes in COVID-19 cases following local economies reopening from lockdown.

15 hours ago - Health

15 states broke single-day coronavirus records this week

Data: Compiled from state health departments by Axios; Map: Danielle Alberti/Axios

At least 15 states broke their single-day novel coronavirus infection records this week, according to state health department data reviewed by Axios.

The big picture: The number of coronavirus cases increased in the vast majority of states over the last week, and decreased in only two states plus the District of Columbia, Axios' Andrew Withershoop and Caitlin Owens report.