Covid-19: French saliva test proves effective in &lsquo real-world&rsquo conditions

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.

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&rsquo 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.