Signage requiring masks is on display outside of a H-E-B supermarket in Austin, Texas on March 3. Texas is one of the states lifting its mask mandate alongside other COVID-19 restrictions, against the warnings of public health experts.

Signage requiring masks is on display outside of a H-E-B supermarket in Austin, Texas on March 3. Texas is one of the states lifting its mask mandate alongside other COVID-19 restrictions, against the warnings of public health experts. / Getty Images

Updated March 5, 2021 at 12:55 PM ET

As several states face criticism for lifting coronavirus-related public health restrictions, a study published Friday confirms that state-imposed mask mandates and on-premises dining restrictions help slow the spread of COVID-19.

The study, published in the Centers for Disease Control and Prevention's Morbidity and Mortality Weekly Report, looked at the impact of state-issued mask mandates and on-premises dining on county-level COVID-19 cases and deaths between March 1 and Dec. 31.

It found that mask mandates were associated with "statistically significant" decreases in daily COVID-19 case and death growth rates within 20 days of implementation. In contrast, allowing on-premises dining was associated with an increase in daily cases 41 to 100 days after reopening, and an increase in daily death growth rates after 61 to 100 days.

"Policies that require universal mask use and restrict any on-premises restaurant dining are important components of a comprehensive strategy to reduce exposure to and transmission of SARS-CoV-2," the study authors wrote. "Such efforts are increasingly important given the emergence of highly transmissible SARS-CoV-2 variants in the United States."

Public health experts including the CDC have long recommended universal masking and avoiding nonessential indoor spaces to mitigate the spread of COVID-19, and the new findings add to a growing body of evidence that such measures are effective.

The study says its analysis did not differentiate between indoor and outdoor dining.

The study's release comes days after the governors of Texas and Mississippi announced they would eliminate mask mandates and capacity limits on businesses, in direct contradiction of CDC guidance to stay the course with such restrictions as the country races against highly infectious variants to get the population vaccinated.

More states have moved to roll back restrictions in recent days. Connecticut's governor announced on Thursday that the state will lift capacity limits on restaurants and other businesses later this month, while keeping its mask mandate and certain other requirements in place. And on Friday, Arizona's governor signed an executive order eliminating business occupancy limits, with distancing and masking protocols to remain in place.

The governors of Texas and Mississippi said that falling case counts and the accelerating pace of vaccinations mean that individuals should be able to make their own decisions about COVID-19 precautions. President Biden on Wednesday slammed those states' decision to roll back restrictions, calling it "Neanderthal thinking."

CDC Director Dr. Rochelle Walensky told NPR on Wednesday that recent progress against the virus may be stalling, and the next few months will play a pivotal role in determining its course. As in recent COVID-19 briefings, she encouraged Americans to follow public health guidance like masking and social distancing even if they are not mandatory.

At White House COVID-19 Response Team briefing on Friday, Walensky noted this study is far from the first to demonstrate the benefits of mask wearing and risks of in-person dining.

"This report is a critical reminder that with the current levels of COVID-19 in communities and the continued spread of more transmissible virus variants — which have now been detected in 48 states — strictly following prevention measures remains essential for putting an end to this pandemic," she said. "It also serves as a warning about prematurely lifting these prevention measures."

She added that cases and deaths are "still too high," and have plateaued for more than a week. Case counts continue to fluctuate around 60 to 70 thousand per day, with confirmed daily deaths hovering around 2,000.

Briefing officials noted that while the idea of getting back to everyday activities may sound appealing, both the U.S. — and now Europe — have seen that cases surge when prevention measures lift.

Andy Slavitt, senior adviser on the White House COVID-19 Response Team, urged people to wear a mask "not forever, but for now."

"This is not just the voice of cautious public health experts," he said. "It is what businesses who want to remain open, and many public officials, of both parties, who have lived through the last year are saying."

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Tags: COVID-19 prevention  indoor dining  mask mandates  Series: The Coronavirus Crisis