UK bets on PCR self-tests, but is it reliable and feasible?

This swab, would you be willing to insert it yourself deep into your nose?

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• To develop its coronavirus screening capabilities while reducing costs and health risks, the United Kingdom is using self-tests.

• These are PCR self-tests where it is the patient himself who takes his nasopharyngeal swab with a swab.

• Patients and biologists doubt the feasibility - and therefore the reliability - of such a system.

It's one of the words of the year: swab.

Named after this long cotton swab inserted deep into the nose during a PCR screening for Covid-19.

What if you were asked to do this nasopharyngeal swab yourself?

Would you do it?

This is the strategy adopted by the United Kingdom to increase its screening capacities while limiting the costs and risks of exposure of technical staff to the coronavirus.

The procedure, reserved for symptomatic people, provides for the free provision of a screening kit delivered at home, to be carried out oneself or to be collected and carried out in a screening center indicated by the British health authorities.

The patient self-extracts twice: in the back of the throat and in the nose.

But is the method reliable?

Does she have a chance to arrive in France?

Are the general public ready to self-test by PCR?

“Do the nasal swab myself, never!

It's impossible !

"

After a long rise in power, France is now able to screen two million people per week.

On the side of medical biology laboratories, "we are already working 24 hours a day, 7 days a week and we are at the maximum of our capacities,"

 the Union of Young Medical Biologists (SJBM)

indicated recently at

.

So, is the PCR self-test a serious avenue for ensuring French screening capacities?

“PCR screening is a technical gesture that must be performed by someone trained for this purpose,” recalls Dr François Blanchecotte, president of the Syndicat des biologistes.

However, the general public is precisely not trained in such a gesture.

In the United Kingdom, pictorial instructions are given to Britons invited to self-test.

But in practice, not sure that everyone can do it.

After showing Covid-compatible symptoms, Hamid recently had a PCR test.

“Some find it just a bad time to go through.

Well I found that it was downright painful, like when mustard comes to your nose, but a thousand power!

So, for the sixty-year-old, it is out of the question to carry out this sample himself.

“The technician inserted the swab deep enough into my nose, and left it there for about ten seconds, wiggling it.

It burned me, I couldn't wait for it to end!

So do the nasal swab myself, never!

It's impossible.

And in practice, I would be too afraid to push it too deep and hurt myself ”.

Same feeling for Laure, tested twice in the context of her professional duties: “I'm sure I wouldn't dare to push the swab deep enough, it's more reassuring that a healthcare professional takes care of it.

And it is also more reassuring about the effectiveness of screening.

If I was the one doing the nasal swab, I would have less confidence in the result.

If it was negative, I would wonder if it was because I did wrong ”.

And it is not Dr. Blanchecotte who will contradict her.

“As a biologist who performs numerous PCR daily, I have already undergone this screening myself to avoid any risk of contamination.

And I can assure you that I would be unable to insert a swab into the back of my nose myself.

So I have doubts about everyone's ability ”.

The unreliability of saliva samples

"Strictly, the swab in the back of the throat, why not", concedes Hamid.

Moreover, the saliva test, awaited for months, offers hope in the simplification of screening campaigns.

"Emmanuel Macron has indicated that he would like the rapid arrival of saliva tests by self-sampling, which everyone could perform at home," said Dr. Blanchecotte.

If tomorrow, we have a saliva test capable of detecting viral particles and which is easy to perform yourself, obviously that would be ideal ”.

If saliva tests have been validated by the High Authority for Health (HAS), “they are not as reliable as PCR, regrets Dr. Blanchecotte.

The problem is that in the saliva there is much less virus than in the nose.

In addition, in saliva, there are enzymes that degrade the RNA of the virus, which explains why RT-PCRs on saliva do not work very well, regrets the biologist.

We tried but currently, we do not recommend it to our patients, because there is a problem of conservation, quantity of saliva, and action of enzymes between the moment when the sample is taken and when the sample analysis is performed ”.

No return from the British authorities

But reliable PCR tests on saliva samples could be developed.

“What would seem reliable is 'cold' PCR, with a modified amplification protocol, which could be performed with a certain amount of saliva - which could then easily be self-collected.

There are machines around the world that would be able to perform these tests.

We are trying to find out if it is possible to acquire them, because they would have greater reliability and would allow a result to be obtained in less than an hour.

Currently, there are two suppliers of this machine, and we would like to test it with saliva samples from patients known to be positive to test its effectiveness.

But for the moment, it is still very hypothetical ”.

In the United Kingdom, several hundred thousand Britons have so far self-tested by PCR.

But British health authorities have not revealed precise data on the results obtained.

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• Covid 19

• UK

• Coronavirus

• Health

• epidemic

• Screening