Covid-19 tests: does the massive screening policy still make sense with Omicron?

For several weeks, there has been a rush for self-tests. Pharmacies are being taken by storm and queues are stretching out in front of analysis laboratories. But is it really necessary to test massively at this stage of the epidemic since it seems unlikely to prevent the circulation of the virus and stem its spread? The question divides scientists.

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The surge of Covid-19 contaminations, which results in a rush on the tests, makes some doctors doubt the interest of continuing such massive screening, while others still see it as a way of curbing the epidemic runaway. The scenes have been repeating themselves for weeks now: from thedawn, queues form in front of medical analysis laboratories and pharmacies to take the test which will give a “positive” or “negative” result.

The figures of the vague current, carried by a variant Omicron extremely contagious, have something to make you dizzy: a record number of contaminations accompanied by an unprecedented number of tests with more than 8.3 million carried out last week. So much so that some wonder if at this stage of the epidemic, it is necessary to continue this massive screening policy, which is very expensive and complicated to organize.

« Large-scale testing is probably unnecessary now, decides with AFP the emergency doctor Yonathan Freund. Does doing more than a million tests per day limit the virus circulation ? I don’t believe it, or at the margin “. Today, he continues, “ it is too late, we have lost control, we must accept the fact that the virus will circulate “. A bombshell ? ” Many think the same thing but the subject is still taboo », He believes.

An essential tool for monitoring the pandemic

This view does not seem, in any case, to be shared by various epidemiologists who see the tests as an essential tool for monitoring the disease. pandemic. But also and above all one way, among others, to stem its progress. ” Before, a contact case should self-isolate, now that this is no longer the rule, it is important to know if you are a carrier of the virus or not, notes epidemiologist Pascal Crépey. The tests are not a handbrake that can stop the car, but it’s still an engine brake “. And according to him, ” it is wrong to say that everyone will be infected with Omicron no matter what ».

Because everything depends on the reproductive capacity of the virus which can be limited by a combination of measures. Screening is potentially one of them even if, like any other measure, it is not 100% effective. This reproductive capacity is very important but remains to be specified because, at this stage of theepidemic, many uncertainties remain around the variant Omicron. « We do not yet know enough about its contagiousness, nor its consequences to allow us to modify the screening strategy. “, Estimates the professor in epidemiology Mahmoud Zureik. If it turns out that if it becomes a endemic virus like the common cold, the question of the relevance of the tests will arise, but we are not there yet ».

The rush for self-tests

If the screening tests stay at eyes certain relevant ones, they still need to be accessible and carried out at the right time. Gold, “ we are overwhelmed, we are reaching the limits of the system, breathes Jérôme Grosjean, medical biologist. The other problem is that all the tests are a bit on the same level today but they do not have the same predictive value. “. Many people now prefer antigenic tests, accessible without an appointment, for a faster result but less reliable than the tests PCR, more difficult to access.

For several days, the autotests are also attacked: but again, the result is less reliable than PCR and the risk of possible handling error. La High Authority of Health (HAS) recently considered that there was no evidence to support a loss of clinical sensitivity of antigenic tests and self-tests for the detection of the Omicron variant, recommending the extension of their use in persons with contact.

« A negative self-test should not be 100% reassuring », Sums up Jérôme Grosjean. But it’s always ” better than nothing ».

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