The reference screening test in France is the nasopharyngeal swab test, the RT-PCR. Screening is one of the key steps to curb the spread of the coronavirus, by isolating patients early. The test strategy is evolving, in particular with the arrival of EasyCov® saliva tests.
Quick and helpful EasyCov® saliva tests for symptoms
In its press release dated November 28, the French National Authority for Health issues its opinion on EasyCov® saliva tests. It is a system “integrated”, Whose sensitivity is satisfactory (84%) for people with symptoms of Covid-19. As a reminder, sensitivity is the ability to detect as many patients as possible. When referring to the RT-PCR test, the performance of the saliva test is less precise. However, the latter has other advantages, which are not negligible in times of health crisis. EasyCov® provides results in approximately 40 minutes, compared to several hours minimum for the nasopharyngeal swab test. In addition, it is suitable for symptomatic people, for whom the RT-PCR test is impossible or difficult to perform, such as for children, people with mental disorders or people of very advanced age. Therefore, HAS supports the use of this test and its reimbursement. A confirmatory test will be requested, if the test is positive. On the other hand, the EasyCov® test is not recommended, for the moment, for asymptomatic people, because its specificity is only 92%. However, to limit false negatives to less than 1%, the HAS requires “99% specificity”. Depending on the advancement of scientific knowledge, this may change.
RT-LAMP saliva tests
The RT-LAMP test consists of detecting the genome of the Sars-Cov-2 virus, using a saliva sample. It is also intended for people “in cases where nasopharyngeal swabs – very invasive – were not possible or difficult”. Studies have not shown strong enough data on its effectiveness in asymptomatic people. For patients with symptoms, the findings are the same. The clinical sensitivity of these tests is lower than the recommendations of the HAS (75% against 80%) as well as its specificity (94% against 99%). RT-LAMP tests therefore cannot be included in the screening and diagnostic strategy for Covid-19, according to the opinion issued by the HAS.
The course of the saliva test
Concretely, the person projects saliva into the tube, intended to collect nasal secretions during a PCR test. It is also possible to collect saliva using a swab. All health professionals can do it, but also people themselves (self-test). Saliva tests are painless and generally better tolerated by patients.
