A rumor spread this month in San Francisco via WeChat, a Chinese message and social media app, that employees at several Chinatown businesses were carriers of the potentially deadly coronavirus. One of the businesses was AA Bakery and Cafe, a Chinatown mainstay that typically has a line of customers out the door. Following the rumor, it was a virtual ghost town.

“There was somebody who spread a completely false rumor, which we had our Department of Public Health debunk,” said city Supervisor Aaron Peskin, whose district includes Chinatown. “There are suspicions in the community about who did it, and the allegations are that it was a competitor who was spreading these rumors.”

In Chinatowns from London to Boston to San Francisco, business owners and restaurateurs have reported sharp sales declines in the weeks since Chinese officials identified the novel coronavirus, first detected in Wuhan in late December. The steep drop in business, reportedly as much as 70 percent in Manhattan’s Chinatown, is not just based on consumer fears of the contracting the virus, owners say. It’s also due to a decrease in tourists as airlines shut down flights to mainland China.

But as the case with AA Bakery underscores, the outbreak has generated another source of stress in Chinese communities: operators who have apparently used the crisis to sabotage competitors. “If there’s any silver living to an otherwise abhorrent piece of behavior, it wasn’t about xenophobia,” said Peskin. “It was a malicious lie.”

The outbreak has also raised new worries about age-old prejudices against those with Chinese ancestry. There are reports that non-Asian college students are avoiding their Asian counterparts. Restaurants in South Korea, Japan, Hong Kong and Vietnam have reportedly refused to admit Chinese customers. People of Asian descent have reported public incidents in which they’ve been accused of spreading the virus.

As columnists and pundits have pointed out, these incidents have ugly precedents that date back to the 19th century, when Chinese immigrants were viewed as dirty, disease carriers. The racial fearmongering would eventually lead to the Chinese Exclusion Act of 1882, which suspended Chinese immigration. When the first suspected plague victim died in San Francisco’s Chinatown, city officials quarantined the neighborhood, refusing to allow food in or people out. The plague, according to one account, was considered a “racial disease” at the time.

While racism may account for part of the current business declines, some restaurateurs say their biggest hit has come from Asian customers. Jerry Chan, owner of Lanzhou Hand Pull Noodle in Gaithersburg, Md., says he’s seen a 30 percent drop in sales since mid-January. He attributes it to “at least a 70 percent” downturn in Asian customers.

“This season is the travel season for Chinese people because of the Lunar New Year,” Chan says about the holiday, which fell on Jan. 25. “They are more likely to go back to China and come back. The virus can transmit without any symptoms. Due to all of that, there are quite a few fears.”

Chan has talked to other owners of Chinese restaurants in Rockville — a Washington suburb whose population is 20 percent Asian — and he says they’re experiencing a similar drop in sales. Chan says he’s breaking even at the moment. “Hopefully this is temporary,” he adds.

Lydia Chang, director of business development for her family’s Washington-based restaurant empire, says Lunar New Year business took a significant hit, with about half the large parties canceled. But she says that day-to-day business at most of their locations doesn’t depend on Chinese customers exclusively, and she isn’t sure if coronavirus fears are keeping people away. “The trend has been ups and downs,” she says. “Is it significant enough for us to tell? Not precisely.”

Public health experts note that many reasons people cite for avoiding Chinese restaurants are unfounded. People don’t contract the virus through food originating in China, says Amesh Adalja, a senior scholar at Johns Hopkins Bloomberg School Center for Health Security. “It’s a respiratory illness, and that’s how its spreading: through saliva, coughs, coughs, sneezes and direct contact with others who have the virus.”

Despite quarantines and travel bans, Adalja says, the virus has already spread farther beyond China’s borders than we might think. Many carriers have mild symptoms indistinguishable from a common cold or flu, he says, and many reported cases have been identified as coronavirus only because officials are testing the sickest patients. “That severity bias has created a skewed sample,” he says.

He says it’s irrational to avoid Chinese restaurants, since the risk of encountering the new strain will soon exist “whether you’re at a pizza place or a Chinese restaurant.”

In San Francisco’s Chinatown, aside from attempts at corporate sabotage, it’s hard to quantify how much business has dropped at restaurants and bakeries. Eater quoted a spokesman from the Chinese Merchants Association who said foot traffic was down by 50 percent since the public became aware of the virus. But Steven Lee, a partner in the second iteration of Chinatown’s famous Sam Wo Restaurant, says business was already down because of high-profile crime in the neighborhood, including a daylight burglary of a tourist’s vehicle. The virus, with its decrease in Chinese tourism, has dropped business another five percent Lee says.

“If we’re hurting,” Lee adds, “that means the mom-and-pops are hurting.”

At Wok Wiz Tours in San Francisco, which promises tourists from around the world history lessons and culinary experiences, such as dim-sum lunches and tours of a fortune cookie factory, owner Tina Pavao says day-to-day bookings are down. But she’s encouraged that tourists are signing up for later in the spring. “The restaurants I work with, everyone’s trying to keep stiff upper lip for now,” she says, noting that established spots will probably find it easier to weather than smaller, newer businesses with tighter margins. “Hopefully, everything bounces back in a few weeks, but if it goes on long than that . . .”

There are 930 storefronts on the ground level alone in San Francisco’s Chinatown, says Malcolm Yeung, deputy director for the Chinatown Community Development Center. At least a third of them, Yeung estimates, are food establishments.

“We have been hearing from a number of business owners that business is down,” Yeung says. The regulars “are just not coming.”

Peskin says he has heard of at least six banquet cancellations in Chinatown. The banquets, organized by Chinese family associations, are traditionally large affairs, feeding between 500 to 1,000 people. But these cancellations may not be related to fears of the coronavirus, Peskin adds. Some associations are using their banquet money to make donations to fight the virus in China.

“The reality is,” Peskin says, “this is an issue in China, not Chinatown. I am, at every turn, encouraging people to continue patronizing restaurants and public forums, and not cancel events.”

Other public officials have also been telling residents they have nothing to fear. They’re trying to spread this message through every conceivable channel, including Chinese-language media. City leaders are also turning up at major events themselves to reinforce the point. Most notably, San Francisco Mayor London Breed took part in the Lunar New Year parade on Feb. 8.

In New York’s Chinatown, city council members joined local merchants to launch a campaign dubbed “Show Some Love to Chinatown,” encouraging New Yorkers to shop and dine in the district, particularly around Valentine’s Day. Councilmember Margaret Chin, whose district includes Chinatown, noted at a news conference this week that many of her colleagues have visited local eateries for pork buns, egg custards and soup dumplings in a display of solidarity. No cases have been reported in New York.

“Even though we’re suffering from misinformation about the coronavirus,” she said, “this is also an opportunity for our neighbors, for New Yorkers, to come down and support us.”

But public messaging may not work for everyone. Chan, the proprietor of the noodle shop in Maryland, says he considered putting up a sign to ease consumer concerns — maybe to remind them that his restaurant is safe and sanitary. He even talked to a lawyer about the possible wording. Then he got cold feet.

“It might have a negative impact,” Chan says. “I’m afraid that . . . anything to do with the coronavirus will scare away the non-Asian population.”

“I think I just have to wait it out,” he adds.

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