ST. LOUIS 鈥 Mask mandates in St. 不良研究所导航网址 and St. 不良研究所导航网址 County quickly and drastically slowed coronavirus infection rates this summer compared with outlying counties, according to a new study from St. 不良研究所导航网址 University.
But effects of the mask orders were also durable, the study says: After 12 weeks, the average daily growth rate of coronavirus cases in the two urban counties was still 40% lower than in counties without the policy. Moreover, the mandates reduced 鈥渢he unequal burden鈥 on higher-risk groups, decreasing transmission rates in more densely populated areas and on racial minorities, who have been disproportionately infected, the research says.
鈥淚t was something that was fast and effective,鈥 said Enbal Shacham, lead author of the study, and a professor at St. 不良研究所导航网址 University鈥檚 College for Public Health and Social Justice. 鈥淎nd that鈥檚 exactly what we need right now.鈥
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The research reinforces the public health benefits of mask-wearing even as medical leaders 鈥 including one of the study鈥檚 authors, Dr. Alex Garza 鈥 are imploring Missouri Gov. Mike Parson to order a statewide mask mandate and limit gatherings, dining and shopping. As hospitalizations soar, health officials warn of an imminent crisis across Missouri.
鈥淲e are past the time when individual behavior alone can address this disaster,鈥 Garza, chief of the St. 不良研究所导航网址 Metropolitan Pandemic Task Force, said in a press briefing on Friday. 鈥淭he spread of cases are blanketing the state and no locale is safe anymore.鈥
I have great respect for our Governor, I know him to be a caring person. I too appreciate local control. But we are now under uniform threat, like war, it requires a coordinated response. We each give to protect others, we buy time for the vaccine. 鈥淭he wolf is at the door.鈥
鈥 Steve Edwards (@SDECoxHealth)
Parson has resolutely rejected mandates, instead deferring to local officials and urging residents to take 鈥減ersonal responsibility.鈥 His office did not respond to questions from the Post-Dispatch on Tuesday.
Shacham said that the White House Coronavirus Task Force advised Missouri to adopt a statewide mask mandate back in August. At the time, dozens of the state鈥檚 counties were designated in the 鈥渞ed zone鈥 for high virus transmission, and the overwhelming majority of them did not, and do not, have a mask mandate.
The latest data from the task force, which represents the region鈥檚 large health care systems, showed that St. 不良研究所导航网址 and St. 不良研究所导航网址 County have lower per-capita rates of virus-related admissions than other Missouri counties in the metropolitan area.
Shacham鈥檚 study began in early July, when St. 不良研究所导航网址 Mayor Lyda Krewson and St. 不良研究所导航网址 County Executive Sam Page first ordered residents to wear masks in public.
She and her co-authors 鈥 SLU professors Stephen Scroggins and Matthew Ellis, plus Garza, an SSM Health executive 鈥 compared the average daily increase in COVID-19 caseloads in St. 不良研究所导航网址 and St. 不良研究所导航网址 County with that in neighboring Jefferson, Franklin and St. Charles counties, which do not have mask mandates.
In the three weeks before the mandates, both sets of jurisdictions had been seeing similar growth rates for their respective caseloads.
But in the weeks after the mandates, researchers noted a remarkable slowdown in caseload growth in masked-up counties. To illustrate the decrease, they highlighted comparisons at two different intervals: three weeks after the local mask mandates went into place, then 12 weeks after.
After three weeks, average daily case growth in St. 不良研究所导航网址 and St. 不良研究所导航网址 County was 44% less than that of the outlying counties. And after 12 weeks, that reduction changed only slightly, to 40%.
The study also produced a model to estimate the probable growth of virus caseloads in St. 不良研究所导航网址 and St. 不良研究所导航网址 County, if neither had a mask mandate. The model accounted for areas with higher population density, higher proportions of nonwhite residents, and lower median household incomes 鈥 all factors that correspond with higher rates of infections.
But after St. 不良研究所导航网址 and St. 不良研究所导航网址 County adopted mask mandates, 鈥渢he disparity of infection rate by race and population density was no longer significant,鈥 the study says.
Residents in middle- and high-income communities protected themselves from infection by staying at home, the study鈥檚 authors theorized. Minorities and city residents who were more likely to work in 鈥渆ssential鈥 jobs such as grocery stores, health care and public transportation, and couldn鈥檛 stay home, were greater beneficiaries of the mask policies.
鈥淭he mask policy that was enacted in many communities may have provided a more equal approach to reducing COVID-19 infections, as it occurred in St. 不良研究所导航网址,鈥 the authors write.
The virus is now much more widespread. Still, Shacham believes a mask mandate would reduce infections in Missouri by a similar magnitude.
鈥淚t鈥檚 something tangible,鈥 she said, 鈥渢hat we can do right now.鈥
Editor's note: The study has been submitted to an academic journal for publication, and is now being peer-reviewed, Shacham said. Results were featured last week on the U.S. Centers for Disease Control and Prevention's .