There are a number of reasons why banning indoor dining is a difficult choice politically and morally, the restaurant industry and its workers are already facing financial ruin after months of drastically reduced business.
But when it comes to the safety of COVID-19, the science is clear: eating out is associated with an increased risk of coronavirus transmission.
“People talk a lot about overcrowded events, but there are also overcrowded destinations – types of places that are particularly risky and lead to particularly high rates of infection,” said David Grusky, one of the researchers behind a A recent Stanford University study that modeled coronavirus is spreading indoors. “One of these types of places is full-service restaurants.”
Even before states began the long road to reopening their economies, epidemiologists warned that the virus would spread as quickly as possible. Many listed indoor meals among high-risk activities that should only be resumed with extreme caution, if necessary.
Since the spring, Grusky and others have said, emerging science has only strengthened the initial fears of disease experts. Studies have relied on mathematical modeling, mobile phone data, physics and epidemiology to always confirm that mass during a pandemic poses a huge risk.
But even as hospitalizations rise and officials in Massachusetts and the country return to reopening, restaurants in many places remain obviously and often controversial, open.
Restaurant owners and their associations have fiercely defended their business security, stressing the care and cost of enforcing restrictions, including, in Massachusetts, spacing tables at least 6 feet away, placing only groups of six or more people. few, limiting customer service time to 90 minutes and closing until 9:30 p.m.
And some owners and employers have also indicated data that they believe are on their side: the state’s follow-up reports.
Massachusetts contact locators have linked 84 COVID-19 restaurant clusters, a small portion of the state’s 23,888 known clusters.
But scientists call for a careful interpretation of this data. Of the identified groups, almost all of them – 22,487 in Thursday’s report – are classified as “household spread”, meaning that two or more people living together have become infected.
But this information “doesn’t really help us,” said Samuel Scarpino, an epidemiologist at Northeastern University. We know that people living together are likely to spread the disease to each other, he explained, but the first member of the household who became infected had to receive COVID-19 elsewhere, either at work, on errands or outside. in the community.
“What we need to do is figure out how to stop [COVID-19] from entering households “, said Scarpino.
“It’s a bit outrageous that we have so little information [from contact tracing] about places of transmission so late in the pandemic, “said Marc Lipsitch, a professor of epidemiology at Harvard TH Chan School of Public Health. Lipsitch said contact tracking limitations are a national and even international issue, not a Massachusetts-specific one.
But even with state contacts tracking data that provides little evidence of how and where the coronavirus is spreading, Scarpino and Lipsitch both felt confident that restaurants, and especially indoor restaurants, are risky.
Lipsitch pointed out that several types of research help locate the most likely sources of COVID-19 spread: modeling that uses real-world data to predict how many people will be infected in different reopening scenarios; case-controlled studies comparing COVID-positive behaviors with those who are not infected; and basic physical and epidemiological facts about how the virus itself is transmitted.
All of this type of research clearly indicates restaurants as a high-risk activity, Lipsitch said. And the evidence is growing.
In September, the Centers for Disease Control launched a case-control study in which symptomatic individuals requesting COVID-19 tests were asked to list the types of places they visited in the two weeks before they were tested.
The researchers found that those who gave positive results were twice as likely to say they ate at a restaurant, either indoors or outdoors, compared to people who ended up giving negative results. No other framework has shown such a strong correlation with positive cases as restaurants, a finding found that eating and drinking requires people to take off their masks, while most other activities do not.
In November, a group of Korean researchers looked more closely at how the transmission goes from person to person in restaurants. The study, led by Dr. Ju-Hyung Lee of Jeonbuk National University School of Medicine, found that a restaurant outbreak was seeded in five minutes, spreading between two patrons sitting more than 20 meters away. A third person was also infected.
None of the three owners with confirmed cases interacted directly, but the researchers plotted the airflow in the restaurant and found that the ventilation system probably carried drops directly from table to table.
Add to this the Stanford model, also published in November. Grusky and his research colleagues used cell phone data to map how 98 million people traveled through 10 major US cities. They combined this data with the daily number of cases reported in each city to model how people’s visits to certain types of settings predicted the spread of coronavirus.
The model found that two mobility factors – how dense a particular setting is and how long visitors stay – are closely associated with an increased risk of COVID-19 transmission. He also predicts that a city’s decision to open a particular type of framework – full-service restaurants – will increase the number of cases more than any other framework studied by researchers.
High density and long stays are “structural features” of restaurants, Grusky said, which helps explain why they are more model cases than other high-risk settings, including fitness centers, cafes and snack bars. as well as hotels and motels.
Models, case studies, and ventilation charts aside, Lipsitch said the reason the indoor table spreads COVID-19 is simple – and specific to the coronavirus, rather than the restaurants themselves.
“Uncovered mouths, especially open mouths, loud speech and poor proximity and ventilation contribute to the transmission of coronavirus. All this is very clear, “he said.
The fact that the risk factors for this special pandemic map so perfect for indoor restaurants is little more than a coincidence – a deeply unfortunate one for an industry struggling to stay afloat.
“There is nothing mystical about our restaurants,” Lipsitch said. “Whether it’s a restaurant, a gym, or a house of worship, or a room where I go with my best friends and yodel. . . only certain activities spread the virus more efficiently. “
Dasia Moore can be contacted at [email protected]. Follow her on Twitter @daijmoore.