Two Missouri hair stylists who saw dozens of clients while infected with the coronavirus did not pass the illness to any of their customers who were tested, health officials said.
The diagnosis of the two stylists at the same Great Clips in Springfield, Missouri, last month raised fears that 140 customers may have been exposed.
"This is exciting news about the value of masking to prevent COVID-19," Springfield-Greene County Director of Health Clay Goddard said in a statement Monday, referring to facial coverings still mandated in many public places.
Testing was offered to all 140 customers and six co-workers who may have been exposed, the health department said, but only 46 people pursued testing and all tested negative.
Still, the incubation period for COVID-19 among all those potentially exposed has passed, the health agency said. All potentially exposed were quarantined for the duration of their exposure period, it said.
The health department also said Monday that in addition to required masks, the Great Clips had other policies like the distancing of chairs and staggered appointments that likely prevented the spread of the disease.
Health officials said they plan to study the measures. Great Clips Inc. said late last month that area locations had been temporarily closed after receiving threats.
The company said in a statement to NBC affiliate KYTV of Springfield this week that "we care deeply about the well-being of customers, salon staff and the communities we serve, and we are grateful for the health of these individuals."
Missouri hair salons and barbershops had been allowed to reopen after nonessential businesses were ordered closed under a statewide stay-at-home order to slow the spread of the coronavirus.
Missouri Gov. Mike Parson announced Thursday that the state would fully reopen Tuesday. All statewide orders will be lifted after that, but local officials will have authority to put restrictions in place.
As of Thursday, more than 15,300 cases of COVID-19 have been confirmed in the state, with 860 deaths, according to the Missouri Department of Health and Senior Services website.
Across the U.S., more than 2 million cases have been confirmed with more than 114,000 deaths linked to the disease, according to NBC News' count.