LinkedIn icon The word "in". Email icon An envelope. It indicates the ability to send an email.

Getty

In an early-release research letter in the journal Emerging Infectious Diseases, researchers said they found that nine people sitting near one another at a restaurant in China in January got COVID-19, the illness caused by the coronavirus, and that it likely spread because of the restaurant's air-conditioner.

The authors advised restaurants to increase the distance between tables and improve ventilation.

As restaurants look to reopen, experts say they will need to take extra safety measures, such as reducing capacity, having employees wear masks, and capping how long diners can stay there.

Visit Business Insider's homepage for more stories.

Media not supported by AMP.

Tap for full mobile experience.

Three seemingly healthy families were struck by COVID-19 in January after dining at neighboring tables in a windowless restaurant in Guangzhou, China.

Researchers studying the case think that the restaurant's air-conditioner blew the viral droplets of one person who was asymptomatic farther than they might have normally gone. Nine other people across the three families later got sick.

The researchers described their findings in an early-release research letter published in the journal Emerging Infectious Diseases earlier this month. You can see a diagram of the seating plan here.

It's a frightening prospect for people trying to keep a healthy distance from others. But in a potentially hopeful finding for the locked-down restaurant industry, none of the 73 other diners and eight employees in the restaurant at the time got sick, the researchers added.

Read more: The Senate just passed a $484 billion coronavirus stimulus bill. Here's what's in it for small businesses, hospitals, and the public.

"To prevent the spread of the virus in restaurants, we recommend increasing the distance between tables and improving ventilation," they wrote.

For the struggling restaurants desperate to reopen in the coming months, the researchers' findings are evidence that work will not just return to normal after the pandemic, but there might be ways to limit the risk of spreading the virus. There will likely be caps on how long patrons can spend eating, restaurants will operate at lower capacity, air-conditioning or heating may have to stay off, and employees might be advised to wear masks.

Researchers think the source of this outbreak was a 63-year-old woman who did not show symptoms — such as a fever and a cough — until later in the day. She went to a hospital and tested positive for COVID-19.

Within two weeks, four of her relatives had also gotten sick, as did five other diners in two other families, who seemed to have no other connection except for their time in the restaurant.

It surprised the researchers, since the novel coronavirus is transmitted by droplets, or heavy particles that tend not to float farther than 1 meter, and the families were sitting farther apart than that. They said it seemed that the air-conditioning could have blown the viral droplets farther.

The restaurant industry has been hit hard by the pandemic

Since March 1, the restaurant industry has lost over 3 million jobs, the National Restaurant Association said. And one in five US restaurants could close permanently because of the pandemic, according to a UBS estimate.

The National Restaurant Association this week asked Congress for $240 billion to help the struggling industry.

While most Americans have indicated they want to wait before resuming their daily routines, opening up restaurants means reopening a supply chain for restaurateurs, farmers, produce sellers, cooks, and servers.

Restaurants will need new rules when they reopen, but it could vary by state

The researchers who studied the outbreak at the Guangzhou restaurant did not replicate the phenomenon in a lab, and they don't have other cases to compare it to, so their findings have to be taken with a grain of salt.

But William Schaffner, a professor of infectious diseases at Vanderbilt University, said the research letter was a good resource to help us understand what restaurant reopenings would look like.

"We are going to open back up," Schaffner said. "But the trick will be to open slowly, do it in a phased fashion," he said, including "opening restaurants and doing so at half capacity, spacing out the seats."

It's unclear whether spacing and capacity rules could do the trick, though it's highly likely they would be employed anyway — and we could start to see rural areas, which generally haven't been hit as hard by the virus as cities, try them first.

Schaffner, who lives in Tennessee, which had about 7,300 coronavirus cases as of Tuesday, said he had seen the mounting pressure for restaurants to reopen.

Jennifer Horney, the founding director of the University of Delaware's epidemiology program, told Business Insider that she foresees a slow relaxation of states' or regions' emergency orders, which would allow restaurants to reopen with some tweaks to traditional service. Eating out in a state with relaxed guidelines might include paying through touchless methods, using disposable menus, and seeing staff members wearing face masks and gloves.

Scientists say restaurants should reduce capacity when they reopen, but it may be a hard rule to enforce

Horney said that rather than creating restrictions, such as banning air-conditioning or outdoor dining, restaurants might find it easier and just as effective to adapt existing rules, such as those about room capacity.

"Existing regulations, like fire-code occupancy numbers, could be used to set a maximum number, like 25% of usual occupancy, that could be safely served at any time," Horney said.

But Schaffner was skeptical about how to ensure that restaurants adhere to capacity rules.

"Some restaurants will say, 'Listen, we're getting a lot of business. Let's just open up a few more tables. The COVID police are not going to catch us tonight,'" he said.

NOW WATCH: Popular Videos from Insider Inc.