Universal Masking, Limiting On-Site Dining Reduced COVID-19 Spread
What were the factors that really made a difference in reducing the spread of COVID-19 earlier in the pandemic? A CDC model suggests that universal masking and limiting on-site restaurant dining was critical then and remains important now, with new variants emerging. Here is how much those two state and local government actions affected novel coronavirus cases and deaths last year.
ATLANTA – Political debates notwithstanding, modeling from the national Centers for Disease Control and Prevention finds two factors that have proven especially important to mitigate spread of COVID-19.
Those are universal masking and avoiding nonessential indoor space. “Mandating masks was associated with a decrease in daily COVID-19 case and death growth rates within 20 days of implementation,” according to the article in the CDC’s Morbidity & Mortality Weekly Report. “Allowing on-premises restaurant dining was associated with an increase in daily COVID-19 case growth rates 41–100 days after implementation and an increase in daily death growth rates 61–100 days after implementation.”
Background information in the report notes that, because the virus is transmitted predominantly by inhaling respiratory droplets from infected persons, universal mask use can help reduce transmission. It points out that, starting in April 2020, 39 states and the District of Columbia (DC) issued mask mandates.
Starting in March, 49 states and DC also prohibited any on-premises dining at restaurants, although, by mid-June, all states and DC had lifted these restrictions.
Emphasizing that the pandemic isn’t over, despite increasing levels of vaccination, and that emerging variants could lead to new spikes, CDC researchers sought to examine the association of state-issued mask mandates and allowing on-premises restaurant dining with COVID-19 cases and deaths during March 1–December 31, 2020. To do that, they compared county-level data on mask mandates and restaurant reopenings with county-level changes in COVID-19 case and death growth rates relative to the mandate implementation and reopening dates.
Results indicate that mask mandates were associated with decreases in daily COVID-19 case and death growth rates 1–20, 21–40, 41–60, 61–80, and 81–100 days after implementation. On the other hand, allowing any on-premises dining at restaurants was associated with increases in daily COVID-19 case growth rates 41–60, 61–80, and 81–100 days after reopening, and increases in daily COVID-19 death growth rates 61–80 and 81–100 days after reopening.
“Implementing mask mandates was associated with reduced SARS-CoV-2 transmission, whereas reopening restaurants for on-premises dining was associated with increased transmission,” the authors note. “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 (1). Such efforts are increasingly important given the emergence of highly transmissible SARS-CoV-2 variants in the United States.”
The timing of the effects of policy changes varied. While mask mandates were associated with statistically significant decreases in county-level daily COVID-19 case and death growth rates within 20 days of implementation, allowing on-premises restaurant dining was associated with increases in county-level case and death growth rates within 41–80 days after reopening, according to the CDC.
Public health officials explain that prohibiting on-premises restaurant dining might assist in limiting potential exposure to SARS-CoV-2, but that those orders also disrupt daily life and have an adverse impact on the economy and the food services industry. Because of that, CDC offers considerations for operators and customers which can reduce the risk of spreading COVID-19 in restaurant settings.
“COVID-19 case and death growth rates might also have increased because of persons engaging in close contact activities other than or in addition to on-premises restaurant dining in response to perceived reduced risk as a result of states allowing restaurants to reopen,” the authors explain. “Further studies are needed to assess the effect of a multicomponent community mitigation strategy on economic activity.”
Researchers also sought to explain why increases in COVID-19 case and death growth rates were significantly associated with on-premises dining at restaurants after indoor or outdoor on-premises dining was allowed by the state for more than 40 days. “Several factors might explain this observation. Even though prohibition of on-premises restaurant dining was lifted, restaurants were not required to open and might have delayed reopening,” they write. “In addition, potential restaurant patrons might have been more cautious when restaurants initially reopened for on-premises dining but might have been more likely to dine at restaurants as time passed. Further analyses are necessary to evaluate the delayed increase in case and death growth rates.”
The report warns that with “the emergence of more transmissible COVID-19 variants, community mitigation measures are increasingly important as part of a larger strategy to decrease exposure to and reduce transmission of SARS-CoV-2.”