- The coronavirus epidemic has seen an upsurge in recent days.
- While nasopharyngeal tests are the benchmark, saliva tests using the PCR technique were the subject of a study conducted by the Toulouse University Hospital to compare their effectiveness.
- If “the sensitivity which is a little lower than the nasopharyngeal test”, the results are good, assures Pr. Jacques Izopet of the virology laboratory, who recommends their use in mass screening.
While the epidemic of coronavirus knows a
upsurge in the country, the doctrine remains that of “test, isolate, trace”, associated with barrier gestures and vaccination. To screen, laboratories use nasopharyngeal tests, whether PCR or antigenic. But to facilitate the samples, the use of saliva tests is more and more popular. And are displayed as an alternative solution, especially among certain audiences such as children, when Olivier Véran has just announced
the goal of testing one million students and teachers every month.
Less invasive, and therefore painful, some give almost identical results to classic tests according to Professor Jacques Izopet, head of the department. virology laboratory at Purpan University Hospital. With his teams, he conducted a study on the subject which should be the subject of a future publication. “We had a first experience during the first wave and in September we carried out a larger study to assess the performance of
PCR tests performed on a saliva sample », Underlines this specialist.
More than 300 people have thus been tested twice. “We tested nasopharyngeal swabs and saliva swabs in parallel, and we had very good results. We have a sensitivity which is a little lower than the nasopharyngeal test, but higher than what the antigen tests offer. Clearly the same technique PCR whether it is carried out on a nasopharyngeal sample or a saliva sample gives substantially identical results, ”says the practitioner, whose laboratory currently performs more than 1,000 tests each day.
For this effectiveness to be almost similar, the sample must be taken during the first four days of symptoms. The results of this study relate to the saliva tests analyzed using the PCR technique, and not to the rapid saliva tests based on the RT-LAMP technique who have just obtained a reimbursement authorization.
For the time being, the Toulouse University Hospital laboratory is already using this sampling method, in particular for people who have to do tests repeatedly. If the reference test remains the nasopharyngeal sample according to Jacques Izopet, “in mass screening operations”, “saliva tests will be very interesting, for epidemiological purposes to be able to identify the frequency of people infected with the virus at a given time. and carry out precise molecular studies, in particular sequencing studies ”, concludes the specialist.