“How many days before Christmas Eve should a PCR test be performed?” For how many days does it provide immunity? Is contagion still possible? “
The question was asked by Max and has been on several occasions, especially since the arrival of antigenic tests in pharmacy. An IFOP survey conducted for the Odéro medical site, shows that 26% of French people plan to be tested before reuniting with their family for New Year’s Eve. Let us recall in passing that certain politicians such as Laurent Wauquiez, president of Auvergne Rhône-Alpes, or even Renaud Muselier, head of the PACA region and the Regions of France, push for massive screening campaigns before the holidays.
But to come back to Max’s question, it should first of all be remembered that a test has never ensured any immunity. Only vaccines, in this case, are able to protect us from Covid-19. PCR or antigenic tests to speak only of the latter, have only one and only vocation: to detect the presence of the virus in our organism.
The more general question then arises of the advisability of being tested before Christmas Eve? “It may seem, on paper, a good idea”, recognized, Thursday evening during the press conference of the government, Olivier Véran. On paper only.
Overprotection
The Minister of Health warns against “A risk of overprotection. Having a test that is negative when you are asymptomatic does not mean that you are not carrying the virus ”. It should indeed be borne in mind that the incubation period of Covid-19 is three to five days and can extend up to fourteen days. During this entire incubation period, we remain contagious, but the test result will not necessarily be positive.
Lionel Barrand, president of the National Union of Young Medical Biologists, whom we interviewed, agrees: “The test is not a passport to non-contagiousness. Imagine a young person who celebrates on Friday, December 18, crosses paths with carriers of the virus. If he takes the test on Monday or Tuesday, he may be negative. Two days later, he will kiss his grandparents when his viral load is at its highest. “
The Minister of Health, too, projects himself into the hypothesis of a risky New Year’s Eve: “The danger would be that twenty people who share a meal, or who have planned to share a meal for Christmas, decide to be tested and, in confidence, meet at the table, stop the barrier gestures, do not wear the mask, share the same outbreak for several days with fragile people who think they are not risking anything, when in reality the virus is there and the risk of transmission is real. “ And Olivier Véran to implore: “Please don’t use the test as some sort of immunity totem pole. “
For Christmas and the holidays, the only good reflex is barrier gestures and limiting the number of people.
The temptation of the pre-Christmas test can be misleading (false negatives) and saturate the offer of tests, essential for contact or symptomatic people. pic.twitter.com/QppjpLQOCx
– Olivier Véran (@olivierveran) December 10, 2020
Several eminent specialists have however evoked this solution of the test to prevent the upcoming Christmas Eve from turning into a hotbed of contamination. Anne-Claude Crémieux, infectious disease specialist at Saint-Louis hospital in Paris, advises for example “To self-confine during the previous seven days and to take a test before going to see the family”. Same positioning for Gilles Pialoux, head of the infectious disease department at Tenon hospital in Paris, who calls for PCR tests to be preferred “Forty-eight hours before going with the family”.
When you have symptoms, yes, “not for comfort”
Olivier Véran warns against the risk of laboratory congestion. “If there were 10 or 15 or 20 million French people who wanted to be tested in an emergency before going to share the Christmas meal, obviously no health structure in the world would be able to cope with it. “
“People have already made appointments for December 22, 23 or even 24”, confirms Lionel Barrand. The latter does not hide his concern: “If we have two or three times as many tests to do, it’s fine; if it’s four or five, that will be the embolism of the system. And it will come at the expense of those who really need to be tested, such as symptomatic people. “
A perspective that worries just as much François Blanchecotte, president of the national union of biologists. “We must not be overwhelmed by tests that I would call comfort. We must distinguish between people who have symptoms, those who cough, have a fever… These people must absolutely go to a doctor. You can choose, at this time, the antigen test or the PCR test. “
– .
