The American medical regulator has decided to resume using protective masks by US residents vaccinated against COVID-19, based on new information about the coronavirus, the New York Times reports, citing the head of the US Centers for Disease Control and Prevention (CDC), Rochelle Walensky.

In May, Walensky reported that vaccinated US residents might no longer wear masks and do not observe social distance in most cases. However, on July 27, the regulator said that vaccinated people should wear protective medical masks indoors. This recommendation applied to areas of the United States with a high incidence of COVID-19.

“A new study has shown that vaccinated people infected with the delta strain carry a huge number of viruses in the nasopharynx,” the article says with reference to Walensky’s email to the publication.

As noted, the new data contradict previous observations of researchers, according to which vaccinated people with infection with earlier versions of the coronavirus were only very likely to become a source of infection for others.

According to the publication, internal CDC documents say that the delta variant is more contagious than the viruses that cause MERS, SARS, Ebola, colds, and seasonal flu, and can only be compared with chickenpox.

The documents do not exclude that the regulator may not limit itself to recommending the use of masks in certain areas and make their wearing “universal.”