A recent national study adds to the growing body of evidence that mask laws can help slow the spread of the coronavirus and that encouraging people to eat at restaurants can lead to more cases and deaths.
The report was published by the Centers for Disease Control and Prevention on Friday.
CDC Director Dr. Rochelle Walensky said during a White House briefing on Friday that “all is very consistent.” “When you wear masks, you have less cases and deaths, and when you eat at a restaurant in person, you have more cases and deaths.”
The study was published at a time when some states are repealing mask laws and limiting the number of restaurants where people can smoke. Despite appeals from health officials, Texas became the largest state to lift its mask law earlier this week, joining a push by several governors to relax COVID-19 restrictions.
“It’s a good piece of work that makes the case very clearly that in-person dining is one of the most important items that needs to be handled if you’re going to contain the pandemic,” said William Hanage, a Harvard University disease dynamics specialist who was not involved in the research.
The new study builds on smaller CDC reports, such as one that found that infected people in ten states were more likely to have eaten at a restaurant in July, and another that found mask mandates in ten states were linked to fewer hospitalizations.
The CDC looked at counties in the United States that had state-issued mask mandates and counties that permitted restaurant dining — both indoors and outdoors at tables. The research looked at data from March to December of the previous year.
The researchers discovered that mask laws were linked to lower coronavirus transmission, and that changes in new cases and deaths improved over time.
Growth rates were reduced by half a percentage point to nearly two percentage points. While this may seem insignificant, experts say that because of the vast number of people involved, the effect increases over time.
“Each day the that growth rate decreases, the cumulative impact — in terms of cases and deaths — becomes very significant,” said Gery Guy Jr., a CDC scientist who was the study’s lead author.
In the first 40 days after the controls were lifted, there was no substantial rise in the number of cases or deaths. Following that, the growth rate of cases increased by around 1 percentage point, and the growth rate of deaths increased by 2 to 3 percentage points.
The reason for the delay may be because restaurants didn’t reopen right away, and several people were afraid to eat in after the restrictions were lifted, according to Guy.
Furthermore, there is often a time delay between when people are infected and when they become sick, and much longer between when they end up in the hospital and die. In the case of eating out, a delay in deaths may be caused by the fact that the diners do not die, but they may become ill and spread the infection to others, who then become sick and die, according to Hanage.
He said, “What happens in a restaurant does not stay in a restaurant.”
Officials from the CDC did not go so far as to state that on-premises dining should be prohibited. They did say, however, that if restaurants do open, they should take as many precautions as possible, such as encouraging outdoor dining, providing sufficient indoor ventilation, masking staff, and encouraging customers to wear masks while they aren’t eating or drinking.
There were some drawbacks to the research. For example, the researchers attempted to make predictions that took into account other policies that could affect case and death rates, such as bans on large gatherings or bar closures. However, the writers admitted that they couldn’t account for all potential factors, such as school reopenings.
“It’s still difficult to pin down the causal relationships completely,” Hanage said. “However, when you combine this with anything else we know about the virus, it reinforces the message” of the importance of wearing a mask and the dangers of dining out, he said.