The Delta variant of Covid-19 is as contagious as chickenpox, probably has more serious effects than its predecessors and infected people seem to transmit it as much whether they are vaccinated or not, according to official US documents. These findings, which are based on scientific studies, appear on a presentation circulating internally within the Centers for Disease Prevention and Control (CDC), the main health agency in the United States.
The presentation is based in particular on an analysis carried out in Provincetown, Massachusetts, where nearly 900 cases of Covid-19 have been detected after the July 4 National Day festivities, although three quarters of participants in the event were vaccinated. However, there was “no difference” in the viral load of vaccinated or unvaccinated people, according to the presentation of the CDC, which seems to indicate the same degree of contagiousness regardless of the vaccination status.
Recommend again that the mask be worn indoors for vaccinated people
This observation “is the main factor in the change in the recommendations of the CDC” on the mask, explains Celine Gounder, specialist in infectious diseases at New York University: “It is not to protect people vaccinated who, if they are infected, will have mild symptoms, if any, but are found to infect other people. Moreover, CDC documents show that contaminations of vaccinated people are not as rare as previously thought with “35,000 symptomatic infections per week out of the 162 million Americans vaccinated.”
Revealed by the Washington Post, these documents, whose authenticity has been confirmed to AFP, are accompanied by a warning to those responsible: “the war has changed”. Thus, the director of the CDC, Rochelle Walenksy, relied on the data of the presentation to recommend again, for two days, the wearing of the mask indoors for people vaccinated in high-risk areas.
The risk of dying or being seriously ill is divided by ten with a vaccine
Based on international studies, the CDC judge that Covid-19 was initially about as contagious as the flu, but has become comparable to chickenpox – one person infected with the Delta variant transmitting it to eight others on average – and still below measles. Data from Canada, Singapore and Scotland suggest it could be more dangerous, with more hospitalizations and deaths.
The effectiveness of vaccines varies, but in their presentation, the CDC estimates that the risk of dying or being seriously ill is divided by ten with a vaccine and the risk of being infected at least by three. This amounts to saying that the vaccines are 90% effective against severe forms and 67% against infections. For experts, vaccines therefore remain the solution to the health crisis.