The Delta variant of the novel Coronavirus is as contagious as chickenpox, its effects may be worse than those of previous strains and, apparently, vaccinated persons can still transmit it, according to findings contained in official US documents.
The findings, based on scientific studies, are mentioned in an internal presentation circulated at the US Centres for Disease Prevention and Control (CDC), the main health agency in the United States.
The authenticity of the documents, which were revealed by the Washington Post, has been confirmed by French news agency AFP. They come with a warning to health officials that “the war has changed.”
Based on their recommendations, the head of the CDC this week again recommended the wearing of facemasks indoors, including by vaccinated persons.
The presentation is based mainly on testing done in Provincetown, Massachusetts, where close to 900 Coronavirus cases were identified after Fourth of July (U.S. National Day) festivities even though three-quarters of the town’s population – estimated at roughly 2,950 – had been vaccinated.
According to the CDC presentation, there was no difference in the viral loads of vaccinated and unvaccinated people, which would appear to indicate that people were equally contagious whatever their vaccination status.
This finding “is the main factor in changing the recommendations of the CDC” on facemasks, according to New York University infectious disease specialist Celine Gounder. “This is not to protect vaccinated people who, if they are infected, will have mild symptoms, if any, but it is found that they can infect other people,” she told French news agency AFP.
On the other hand, there have been few hospitalisations (seven, so far) and no deaths linked to this new outbreak, according to Massalive, a local information site.
The CDC documents showed that the reinfection of vaccinated persons was not as rare as had been thought: there are 35,000 symptomatic infections per week among 162 million vaccinated Americans.
Based on international studies, the CDC feels the novel Coronavirus was initially about as contagious as the ‘flu but has now become comparable to chicken pox – one person infected with the Delta variant transmits it to eight others, on average – but is still less communicable than measles.
Data from Canada, Singapore and Scotland suggests that it could be more dangerous, with more hospitalisations and deaths.
Vaccine effectiveness varies, but in its presentation, the CDC estimates that vaccination reduces the risk of falling severely ill when infected by 90% and cuts the risk of infection by 67%.