Washington (AFP)
One of the first studies carried out in the United States on the presence of antibodies to the new coronavirus estimates that the real number of contaminations in Silicon Valley in California is undoubtedly more than 50 times higher than the number of officially confirmed cases.
Stanford researchers tested 3,330 Santa Clara County volunteers recruited by Facebook during the first weekend in April and estimate that between 2.5% and 4.1% of the local population has been infected with the virus. coronavirus, that is between 50 and 85 times the number of cases then confirmed in this region.
In their study, posted on Friday and which has not yet been evaluated by a reading committee of a scientific journal, the authors then calculate that the real mortality rate from coronavirus is less than 0.2%.
Antibodies are the immune system's response to infections. They can provide immunity: for some viruses, for life, but for others less than a year.
The method used in this study has limitations, particularly since more white women volunteered in a very Hispanic region, and the team had to adjust the raw data so that the sample was representative of the local population. .
But the authors, including Eran Bendavid and Jay Bhattacharya of Stanford, believe that their weekend study "demonstrates the feasibility of seroprevalence surveys on population samples today and in the future".
This type of blood test, called serology, is indeed simpler than diagnostic tests, which require molecular analysis from a sample taken from the back of the nose. A drop of the volunteers' blood from their cars was taken here. There are several, more or less precise, the rate of "false negatives" can be relatively high depending on the manufacturer.
Other larger studies have been launched in the United States and elsewhere on a larger scale, with the crucial aim of determining how many people have been infected, and how many are still likely to get the microbe.
The results will feed into the decisions of the public authorities as they prepare for deconfinement, in particular in the United States.
© 2020 AFP