Covid-19: PCR, antigens, self-tests … Which screening to choose before the holidays?

Christmas parties in the midst of an epidemic wave. In a few days, the French will be getting ready to reunite with their loved ones to celebrate Christmas and the New Year. But the Covid-19 and its contagious variant Omicron risk spoiling the party. Currently, France records more than 50,000 cases on average each day, unprecedented. To limit the risk of contamination, the government calls on the population to be tested in the coming days. Three types of tests are possible.

This is the benchmark test in France. Carried out by a healthcare professional, RT-PCR tests make it possible to search for the presence of the virus’s RNA. Once the sample is taken from the nostrils using a 15-centimeter swab, it is sent to the laboratory for analysis. In theory, and depending on demand, the results are sent to you in less than 24 hours.

According to the Haute Autorité de Santé (HAS), these are the most reliable tests. Last February, the independent body estimated its efficiency at 92%. All vaccinated people, those with a prescription, contact cases as well as minors can perform a PCR test free of charge (paid for by the State), in a center. For the unvaccinated, who want to make sure that they do not have the virus or wish to have a valid health pass (for 24 hours after the sample), the reference price is 43.89 euros.

If you do not have the patience to wait for your result for several hours, or if you want to carry out your screening close to where you live, it is possible to carry out an antigen test. In principle, the operation is the same as for PCR: a swab is used to take the sample in the nostril in order to find “the antigens present on the surface of the virus”, indicates the Ministry of Health. But rather than being sent to the laboratory, it is placed directly on a reagent. About fifteen minutes later, the result is obtained. If it is positive, it is then advisable to perform a confirmatory PCR test.

Because the reliability of these tests remains lower. According to an opinion from the HAS, their effectiveness is only 67 to 92% in symptomatic people, and can go down to 33% in asymptomatic people. They can be performed in a pharmacy or by several health professionals, such as doctors, nurses or dental surgeons. Free admission applies in the same way as for PCRs. Their price, for the unvaccinated, varies between 22 and 45 euros.

This is the new weapon suggested by the Minister of Health Olivier Véran to fight against contamination during Christmas Eve: self-tests. They too are considered antigenic tests, but can be performed directly by the user, without the help of a healthcare professional. However, the swab goes less far into the nostril than during the more traditional screening. The result is obtained in 15 to 20 minutes.

Available in pharmacies, their effectiveness remains “limited”, admits the Ministry of Health. Even in the event of a negative result, “it is always possible that you are carrying the virus in undetectable amounts”, warns the government. To limit this risk, the instructions for use must be strictly observed.

The HAS has only authorized the most reliable self-tests on the market: they must detect the presence of the virus in 80% of cases in people actually positive, and the risk of false positive must be less than 1%. For the general public, the cost of these self-tests is not covered, but the limit sale price “amounts to 5.2 euros per self-test”, specifies the ministry.