Saliva Test Could Help Many Return to Work

Apr 28, 2020

Governors in the Northeast say they need more COVID-19 diagnostic tests before people can return to work safely. Researchers at Yale are the latest to study a saliva test they say is easier to administer and more reliable than standard nasal swabs. 

Health care workers wear head-to-toe protection to test someone for COVID-19. They have to sample mucus at the back of the nasal cavity with a long swab. 

“I’ve had one and they’re very unpleasant,” says Anne Wyllie, a researcher at Yale School of Public Health. “The risk with that is it can actually cause the patient or the person being sampled to sneeze or cough. You can imagine if you’re that health care worker and you’re in very close proximity, that can carry quite a bit of risk when we know that SARS-CoV-2 [or coronavirus] gets spread by droplets.”

Wyllie and her colleagues say in a new pre-print study they have found a quick way to test for coronavirus that doesn’t require protective gear, or nasal swabs. 

“Saliva sampling is really easy, it’s actually incredibly easy as compared to the gold standard recommended nasopharyngeal swab.”

She says Yale began asking COVID-19 patients and hospital workers to spit into a sterile collection cup when the outbreak began. They’ve continued to run RNA tests on nasal swabs alongside saliva samples. They found the saliva results look more consistent than the nasal swabs.

“The negatives in the swab itself have far outnumbered the negatives in saliva, so to us it is looking more reliable.

Yale isn’t alone. Wyllie says small studies out of New Jersey, California, Australia and Thailand have shown similar success with saliva samples. 

“Hopefully, with that increased data from around the world and more studies testing this and trialing it out, we’ll get that confidence that we can move forward,” Wyllie says.

Wyllie worked on the early study with Dr. Albert Ko, one of Connecticut’s advisors to help the state reopen safely. Wyllie and Ko’s study suggests screening with saliva tests could be a reliable way to make sure workers do not spread the virus to customers or colleagues. 

“If we’re sending especially healthcare workers back into hospital settings or health care settings, that’s one particular population you want to make sure are really truly negative,” Wyllie says, “not negative due to the sample type that’s being taken, or the test that’s being run.”

Wyllie says scientists do not know if other tests for virus antibodies can prove someone is immune to coronavirus. And, antibodies show up when someone is still contagious. So, diagnostic spit tests may be a better way to track and limit new outbreaks, and it’s one Wyllie’s already testing at Yale New Haven Hospital.

“Our health care workers are sampling themselves every three days for testing just to make sure that they are remaining Covid-free,” she says. 

Out of 278 health workers enrolled in the saliva study, eight employees tested positive for COVID-19 during. Five of them got positive results with the saliva test several days before their nasal swabs detected any viral load. 

“Obviously our numbers are still small. We have actually expanded our study population,” Willey explains, “So we have a much larger study population now, we’re seeing similar trends.”

Wyllie says companies could also consider at-home saliva testing, especially for front line workers in restaurants or grocery stores. For now, she says the spit test could save time at drive-through test sites, or help neighborhood health clinics use less protective gear. 

“It does hold a lot of promise, it will take a lot of pressure off of the supply chain. This could be widely implemented very easily.”

Willey says saliva samples could allow for increased testing capacity across the country.

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