Coronavirus: saliva test to prevent workplace infections

A mass surveillance program requiring employees to undergo a Covid saliva test will be rolled out at select workplaces across Victoria.

A COVID-19 saliva test is demonstrated for Victorian Health Minister Jenny Mikakos and Victorian Chief Health Officer Brett Sutton in June. Picture: AAP

A mass surveillance program will be rolled out at select workplaces across Victoria, under which every employee will undergo a saliva test for COVID-19 in a push to combat the spread of the virus and prevent a third wave.

The Peter Doherty Institute for Infection and Immunity is undertaking a workplace saliva test pilot program at three police stations in Victoria where hundreds of officers and other employees are giving samples, with two asymptomatic cases already detected among people who had no idea they had come into contact with the coronavirus.

Following the pilot, it is anticipated that surveillance testing using saliva swabs will be rolled out in coming weeks at high-risk workplaces including abattoirs, industrial food preparation facilities, healthcare facilities and transport and constructions hubs.

The Doherty Institute has been working on refining saliva tests since they first began to be used in blitzes at the start of the second wave of COVID-19 in Victoria. During the police stations pilot, they have been testing three different methods of saliva collection, including spitting directly into a container, sucking on a swab under the tongue then putting it into a test tube, and collecting saliva via a straw inside a tube.

Doherty Institute Deputy Director Dr Mike Catton.

The swab-sucking method has emerged as the preferred option.

Scientists have also perfected a method known as “pooled testing”, where several samples are collected and run through an ­analyser in the laboratory in the same test tube.

The pooled testing method increases the scale at which testing can be done, making surveillance feasible. It also means the surveillance tests are not competing with existing laboratory capacity for COVID-19 throat and nose swab testing.

Doherty Institute deputy director Mike Catton said the surveillance testing would be key in preventing the undetected spread of COVID-19. It has been estimated that at least a third of COVID-19 cases in the community may be asymptomatic. Surveillance testing is also aimed at picking up presymptomatic cases, when the greatest amount of virus is present.

“As we come out of the restrictions, we’re mixing more people with one another, and the idea that someone can take infection asymptomatically into a workplace becomes an increasing risk.,” Dr Catton said.

“We know that there are places of work that are at increased risk of transmission.

“What government and industry are focused on is ways that we can diminish the risk of those workplaces where we know that if transmission gets started it can be ongoing and problematic. And in workplaces where you’ve got people working in close proximity, it’s hard to socially distance.”

“So we want to be able to detect the earliest hints of transmission in places like abattoirs and places in the food industry.”

It’s anticipated that employees at the chosen workplaces will undergo weekly saliva testing, which would not be feasible if standard tests were undertaken.

“It’s no fun having a swab up your nose every week if you’re a worker in a high-risk workplace,” Dr Catton said. “Pretty quickly I’m sure it would feel like sandpaper. So we’re focusing on a more user-friendly approach using saliva but making that it’s as accurate as other approaches.”

The Doherty has established that their saliva testing methods are as accurate as standard PCR-RT testing, which has been estimated to be 99 per cent sensitive and 99 per cent specific.

Workers at the three police stations piloting the testing have been collecting their samples in the presence of a nurse wearing PPE, but Dr Catton said it may be possible for people to self-collect.

“It may be an option that could be explored in the future,” he said.

The aimed time frame for saliva test results is 24 hours.