How to stop the rebound of the coronavirus epidemic? While the obligation to wear a mask is spreading more and more, including in the open air (from Friday, Toulouse becomes the first large city to ban it throughout its territory), all specialists agree that this will not be enough to put a stop to new contaminations.
Admittedly, barrier gestures - putting on a mask, washing your hands regularly, keeping your distance - are important, as Gilles Pialloux, head of the infectious diseases department at Tenon hospital in Paris, reminded us this Wednesday, but they are not enough. . According to work published this Wednesday by British researchers, testing for Covid-19 and tracing the contacts of infected people are essential measures to slow the circulation of the coronavirus.
Carried out effectively, the “test-trace-isolate” strategy, adopted among others by France, would reduce the reproduction rate of the virus (called “R”) by 26%, concludes this team from the Imperial College of London. Reproduction rate refers to the average number of people infected with each carrier of the virus. Above "1", the epidemic develops, below, it regresses.
Efficient tests if they are fast
In France, the “R” has been around 1.3 since the end of July, according to the French public health agency. “Our results show that testing and tracing can help reduce the rate of reproduction, but only if it is done efficiently and quickly,” says Nicholas Grassly, professor in the School of Public Health at Imperial College, and lead author of this study published in the journal "The Lancet Infectious Diseases".
The 26% drop in the reproduction rate of the virus is obtained on condition that the tests are carried out as soon as the symptoms appear, that the results are returned within 24 hours, that the isolation of people in contact with the patient is done also within 24 hours and that at least 80% of infected people and their contacts are identified. Ambitious criteria, far from being respected in France.
In France, the time between the onset of symptoms and the time the test takes place is on average 3.5 days, according to Public Health France. And it often takes several more days to get results. Even in countries that come close to these criteria - South Korea, Taiwan and Germany in particular - this would still not be enough. One of the avenues put forward by British researchers to further reduce the “R” is the weekly screening of risk groups such as health professionals and social workers, even in the absence of symptoms.