More reliable than nasal swabs?
A recent study has found the results of saliva tests may even be more reliable than those from nasal swabs. People might also be more willing to get regular, repeated tests if they do not involve a painful procedure.
When a pupil in France is suspected of having the virus, his or her whole class may be sent home until the Covid-19 test results come back. If the child tests positive, the whole school may be closed. More than 20 schools have already been forced to close across France since reopening just last Tuesday.
With saliva tests, a school nurse could quickly test a child on the premises and, if the illness turns out to be nothing more than a fever or a stomach bug, the school can continue operating normally. The same practices could be applied to offices as well as airports or other transport hubs.
Similar to a pregnancy test
A sample of saliva (one of the main vectors of the virus) is placed in a test tube with reagents heated to 65°C. After less than an hour, medical staff can simply read the result with the naked eye. This is in contrast to the current nasal test method that requires several hours of laboratory processing and extensive equipment and reagents, and with results often not delivered for days.
France is already a European leader in terms of saliva testing. A revolutionary test called EasyCov was developed in less than three months by the Sys2Diag laboratory in Montpellier.
This test is similar in ways to a pregnancy test. The colour of a saliva-soaked tablet will indicate whether or not virus antibodies are present without any need to go to a laboratory for analysis.
“To develop and mass produce a test in just three months, it is not enough to invent something in a lab, you have to quickly combine the clinical and industrial aspects. When you have all three together, you go fast and you get it done," said project leader and biologist Franck Molina to the French National Center for Scientific Research.
The principle underlying this saliva PCR test is the same as for the classic nasal PCR, but the process is much faster and easier. “PCR tests are seen as the gold standard, the most reliable one at the moment,” confirms Luke O’Neill, professor of immunology at Trinity College Dublin, speaking with FRANCE 24. “The dose of the virus in your body determines your level of infectiousness. The lower the dose you have, the less likely it is you will infect other people.”
www.france24.com
