Homeowners rest assured: Thieves are not posing as health officials testing for the coronavirus.
A particularly viral hoax has spread across local news outlets, police departments and social networks cautioning citizens in various parts of the world to beware of scammers posing as "coronavirus testers," sometimes in hazmat suits, determined to break into homes.
Despite reports from news agencies and police departments from the United States to South Africa and the U.K., there does not appear to be any evidence of the viral urban legend occurring in real life. But articles and posts around the world warning of the phenomenon have garnered millions of shares on Facebook.
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NBC News contacted several police departments that issued warnings about door-to-door scammers. None said that they had substantiated reports of such activity, and many said they were pushed to respond due to concern on social media.
The rapid and international dissemination of the warnings shows how false or misleading information can end up in legitimate channels, even those that are looking to serve the public interest, misinformation experts told NBC News.
The hoax offers regionalized versions of the same narrative, with the fictitious robbers posing as CDC officials in American iterations, and Red Cross or the U.K.'s National Health Service in others. Similar hoaxes predate the coronavirus, including some that used the upcoming U.S. census in place of the coronavirus.
Variations of the alleged hoax popped on social media up in early March. These were amplified and legitimized by police departments who issued warnings to the public despite little to no evidence of door-to-door scammers.
Claire Wardle, executive director of First Draft, a nonprofit dedicated to tackling misinformation, said that government agencies including police departments need to be "triple checking" the information they release to avoid eroding public trust.
"Governments are worried about the economic impact, health supplies and food logistics, but I don't think government agencies are prepared for real-time debunking," she said.
Wardle said many of coronavirus hoaxes currently circulating rely on familiar false narratives.
"We are seeing a lot of templated hoaxes right now," Wardle. "If they worked before, why come up with something new."
The Piscataway Township Police Department in New Jersey was among the first police departments to release a statement on its Facebook page on March 10, advising residents that "representatives from the Centers for Disease Control and Prevention are not going door-to-door to conduct coronavirus-related surveillance."
The department acknowledged that there had been no reported incidents in the area, but said it was responding to social media posts about such a scam.
Other New Jersey police departments followed suit, and the story was picked up by local news outlet My Central Jersey. In total, the posts have received hundreds of thousands of shares on Facebook the last week.
Since the police reports went viral across Facebook in the U.S., the rumors have evolved to include references to the scammers wearing protective clothing.
"These people are pretending to test for COVID and going door to door," wrote one person in Pasadena, California on hyper-local social network Nextdoor along with a picture of four people wearing what appear to be white hazmat suits. "They are imposters and are robbing homes. DO NOT OPEN your door to these people."
The city of Pasadena subsequently posted a. A spokeswoman for the city said that they had a "few reports on one block but couldn't locate the person they were referring to."
Police departments in New York, Texas, California, Ohio, Florida and Arkansas issued warnings to the public that were picked up by local media. Most of them referred to the CDC but some, including Kent County in Michigan, said that scammers were pretending to be from the Red Cross.
Palm Beach County Sheriff's Officeon Thursday stating that "people in white lab coats, masks & gloves are knocking on doors stating that they're from the Department of Health of the CDC." Palm Beach Police issued a similar warning Friday.
"We didn't have any incidents of anyone going round to scam people, but we wanted to warn the public instead of waiting," said Michael Ogrodnick, public information officer for Palm Beach Police.
On the same day, New York state Attorney General Letifia James published a statement about the scam referring to "reports of Otsego County residents" being targeted by scammers.
A spokeswoman for the Otsego County health department told NBC News that it had not received calls from members of the public about this scam, but that she had heard that there were social media posts about it.
Joan Donovan, the director of the Technology and Social Change Project at Harvard's Shorenstein Center, warned of a "media effect" that could drum up fear of a baseless rumor at a time when reliable information matters more than ever.
"With this rumor, there are invisible intruders, along with next-level fears of who might be a carrier and who isn't," Donovan said. "These rumors get dangerous with that added fear and suspicion."