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Covid-19: French saliva test proves effective in ‘real-world’ conditions

A firefighter takes a saliva sample from a colleague who is being tested for the coronavirus at a fire station in Marseille, France on September 22, 2020.
A firefighter takes a saliva sample from a colleague who is being tested for the coronavirus at a fire station in Marseille, France on September 22, 2020. © Eric Gaillard, Reuters
5 min

EasyCov, a French saliva test for Covid-19, has confirmed that it can be as effective as traditional nasal swabbing, France’s National Centre for Scientific Research (CNRS) announced on October 5, marking a major step for a type of screening that is less intrusive, less expensive and much faster.

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The mouth instead of the nose? Supporters of saliva screening tests to detect Covid-19 won a significant victory this week with the publication of the "real-world" results of EasyCov on October 5.

This test, developed jointly by the CNRS and two private sector companies (Alcediag and SkillCell), succeeded in detecting 87 percent of positive cases among 220 people who had arrived for screening at the Montpellier University Hospital since September 16.

In terms of accuracy, EasyCov is "in the high range of results compared with other tests", says Franck Molina, a researcher at the CNRS involved in the development of this screening solution, speaking with FRANCE 24. Conventional nasal screening tests have a success rate of "between 70 percent and 90 percent", Molina points out.

Effective for asymptomatic people

In June, EasyCov was shown to work on patients admitted to hospital who were already showing symptoms. This time, however, the French team confirmed the trial worked on people both with and without any symptoms who arrived for spontaneous screening. These subjects were subjected to the traditional nasal test and also agreed to provide a saliva sample.

The success of this experiment appears to confirm the effectiveness of this type of screening on asymptomatic individuals.

"Of the eight asymptomatic individuals tested, the saliva sample identified all eight," Molina told the Huffington Post.

The result does, however, contradict a recent report by the French National Authority for Health (HAS), which said that saliva tests were not as reliable for asymptomatic individuals.

"This (HAS) statement took us all by surprise," admits Molina. Other recent international studies had supported the accuracy of saliva tests on asymptomatic people. Japanese scientists from the University of Hokkaido published encouraging results for Covid-19 screening using saliva samples in the journal Clinical Infectious Diseases at the end of September.

>> Could saliva tests be a Covid-19 game changer in France?

These advances in saliva screening techniques are good news for several reasons in the fight against the spread of Covid-19. Firstly, these tests are far less physically intrusive than tests that look for signs of the virus in the nasal cavity. "This is a very important consideration to persuade the population to accept these tests," Molina says.

Secondly, they are faster and cheaper. For the nasal test currently in use, called RT-PCR, it is necessary to use a "heavy and expensive machine", explains Molina. Roughly thirty cycles of heating and cooling are required for each sample taken in order to obtain a result, a process that can take several hours. The team behind EasyCov promises a result in forty minutes.

To do this, the test is based on a new technique called RT-LAMP, which requires only two heating cycles and can be carried out with "simple and portable" equipment, according to the French team.

A complementary solution

The idea is not to flood pharmacies with EasyCov and make it available as a home-use kit. In France, allowing everyone to test themselves "would require the adoption of specific regulations, which can take months to process and it’s obviously not compatible with this current health emergency," says Molina. As it stands, the EasyCov test must always be performed by a doctor or healthcare personnel.

EasyCov will instead complement the systems already in place. "As it is flexible and easy to deploy, it can be used as in places where rapid or repeated testing is required," says Molina. Nursing homes, airports and schools would be ideal locations for saliva testing.

In more general terms, Molina believes that the deployment of this test can help avoid a dreaded second lockdown as the number of positive Covid-19 cases continues to rise in France. "At the moment, outbreaks of contamination are mainly in businesses and circles of friends. Saliva screening would enable rapid intervention to help control the spread of the virus," says Molina.

The use of saliva tests would put France back in the international race to advance techniques for dealing with the pandemic. In the United States, the Food and Drug Agency (FDA) has already authorised five different saliva tests, which are in use in universities and by sports organisations. Israel has also begun to use them, as have South Korea and Singapore. Screening in some airports, such as in Djibouti, is also done by saliva sampling.

"France was ahead of the game in June, but our progress dragged a bit during the summer," admits Molina. He hopes that the conclusive results of this latest test in real-life conditions will overcome any reluctance from the authorities. French researchers must now get the green light from the HAS and then Molina says EasyCov is ready to be deployed on a large scale.

This article has been translated from the original in French.

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