Mask mandates were effective as the Delta variant of the coronavirus was driving a surge in Covid-19 cases across Missouri, according to an analysis that the state’s Department of Health and Senior Services conducted in early November.
But the state did not immediately share that data with the public. Instead, the information was released on Wednesday, a month later, because of a public records request by The Missouri Independent, a nonprofit news organization that reported the findings, and the Documenting Covid-19 project at the Brown Institute for Media Innovation.
The records include an email dated Nov. 3 from the director of Missouri’s Health Department to a staff member in the governor’s office. The email included two graphs that compared the rates of reported Covid-19 cases and deaths in parts of Missouri with and without mask mandates.
The director, Donald Kauerauf, said in the email that there were many variables to account for when assessing the effects of mask requirements in Missouri this year, but that the analysis ultimately showed that such requirements were effective.
“I think we can say with great confidence reviewing the public health literature and then looking at the results in your study that communities where masks were required had a lower positivity rate per 100,000 and experienced lower death rates,” Mr. Kauerauf wrote.
The analysis compared the reported case and death rates in the parts of the state without mask requirements to rates in St. Louis, St. Louis County, Kansas City and Jackson County, where mask mandates had been in place.
The study looked at the period from April to October, when the Delta variant was driving an increase in coronavirus infections worldwide.
During that time frame, there were 15.8 cases per day for every 100,000 residents, on average, in the areas that required masks, compared with 21.7 cases per 100,000 residents in unmasked communities, according to The Missouri Independent’s analysis of the data. Regions without mask requirements recorded one death per 100,000 residents every 3.5 days, compared with one death per 100,000 residents every five days where masks were required, The Missouri Independent said.
Gov. Mike Parson, a Republican, has said he supports wearing masks to slow the spread of Covid-19, but he has repeatedly spoken out against mask requirements. In July, he said on Twitter that issuing mask mandates while a vaccine is available eroded public trust. “The vaccine is how we rid ourselves of COVID-19, not mask mandates that ignore common sense,” Mr. Parson wrote.
Mr. Parson’s office and the state health department did not immediately respond to requests for comment on Thursday.
In Missouri, new cases have risen from a daily average of about 1,000 in early November to more than 2,000 this month, and hospitalizations are up 32 percent over the past 14 days, according to a New York Times database. More than 15,540 people have died from Covid-19 in Missouri, according to the database.
In late November, a circuit court judge in Missouri ruled that public health orders issued by local health departments to prevent the spread of the coronavirus violated the state’s constitution.
Mask are still required, however, in St. Louis and St. Louis County. Kansas City ended its requirement on Nov. 5, and the Legislature in Jackson County voted to end its mask requirement in early November.
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Nick Dunne, a spokesman for Mayor Tishaura Jones of St. Louis, said city officials believed St. Louis’s mask mandate was still legal, despite the circuit court order. In response to the state health department’s analysis, Mr. Dunne said, “It tells us what public health experts have been telling us all along, which is that masks are an effective tool for reducing community transmission of the Covid-19 virus.”
In November 2020, Missouri’s hospitals asked Mr. Parson to issue a statewide mask order as hospital administrators struggled to find beds for Covid-19 patients.
Dave Dillon, a spokesman for the Missouri Hospital Association, said on Thursday that because vaccines were available and there were now more options for treating Covid-19, the request for a statewide mask order was “an artifact.”
Mr. Dillon said the association still encouraged people to use masks and follow social distancing guidelines. “Since we’re still in Covid-19 response — with a growing positivity rate and hospitalization numbers — our position will evolve as the science and public health guidance evolves,” Mr. Dillon said in an email.
Across the country, four states and several counties and cities have mask mandates. On Thursday, President Biden extended until mid-March a requirement that travelers wear masks on airplanes, trains and buses and in airports and transit stations as part of a broader strategy to combat Covid-19. These measures come as scientists and public officials prepare for a possible increase in coronavirus cases during the winter and seek more information about a new variant, known as Omicron.