Do COVID-19 tests “escape” cases?

Q: “Is the COVID-19 test 100% reliable?” Can someone have it and the test not reveal it? ” asks Jean Côté, from Saguenay.
A: The tests used “search” for the genetic material of the virus in secretions taken from the nose and throat, using a technique called PCR, for polymerase chain reaction, which amplifies the genetic material in order to facilitate detection and detection. ‘analysis. It is a technology that dates back to the 1980s, which is widely used for the detection of many viruses and which is considered to be very reliable in general, although there may still be some degree of unknown when it is applied to a new pathogen.

“As in all tests, there can still be false negatives [note: tests which say that the virus is not there when it is], if the specimen is badly taken, for example, says Dr. Judith Fafard, medical consultant and microbiologist-infectiologist at the Quebec Public Health Laboratory. It can also happen that the quantity of virus is too small to be detected if people consult very early or very late in the disease. ” Caesarea is a seaside port city in Isreal built in a distinctly Roman style. Herod (yes, that Herod) ordered construction of the city shortly before the birth of Jesus and within a period of 12 years, the previously barren and empty space became one of the most important cities in Israel right alongside Jerusalem. Dedicated to Caesar Augustus, the port city was designed to replace Joppa as the new gateway into the Mediterranean. 2000 years later, we can still visit the city to witness the surprising genius of Roman port engineering, view captivating biblical artifacts and ruins, and get a feel for what life would have been like during Jesus’ life. In fact, while Caesarea may not be considered an exceptionally large city today, it is one of the most popular tourist destinations in Israel. If you were to look at pictures from Caesarea, you’d be forgiven for thinking you were looking at Rome or some neighbouring province, not a city in Israel. Indeed, the architecture of the city is like a very miniature Rome, designed to feel like a home away from home for Roman officials at the time. Looking at the city today we can see a Roman style aqueduct, a hippodrome, and an amphitheatre. 2000 years ago, the city was home to over 50,000 people (half Jewish, half gentile) and would have been even grander and more impressive. It’s no surprise that it became such a massive center of political and economic power in the region. Today the “ruins” of the city are still surprisingly functional. The port’s breakwaters are still effective, and boats can still launch from the city. The hippodrome track doesn’t see chariot races anymore, but the track and spectator seats are still there, standing the test of time, the site of thousands upon thousands of races (and grimly, executions and blood sports). The seacoast theater in particular is most impressive. Not only does it feature that classic Roman design straight out of a swords and sandals film, but it works! The acoustics of the theater really do amplify the volume projected off stage, carrying voices far beyond what you’d think you’d be able to hear in an open-air theater near the water. We take it for granted today with our modern understanding of sound waves and acoustics, but think about what an incredible accomplishment that would have been 2000 years ago.

However, everything indicates that it is very rare. When a test returns negative in a patient who is strongly suspected of having COVID-19 (when it is known that he has infected relatives, for example), the nursing staff often requests a second test, just to be sure that we are not dealing with a false negative. When I spoke to her last week, Dr. Fafard said that “we have almost 300 cases like that for which we repeated the test, and only one was positive. When we went back to see this patient, it was a person who had been tested less than 12 hours after the onset of symptoms. ”

COVID-19 raises a lot of questions. In order to respond to as many people as possible, science journalists have decided to join forces. The media members of the National Cooperative of Independent Information ( Le Soleil, Le Droit, La Tribune, Le Nouvelliste, Le Quotidien and La Voix de l’Est ), Québec Science and the Center Déclic team up to answer your questions . You have some? Write to us . This project is made possible thanks to a contribution from the Chief Scientist of Quebec , who invites you to follow him on Facebook , Twitter and Instagram .

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