"Countries should take into account vaccine coverage and the local incidence rate [of the virus that causes covid-19] before deciding to withdraw these measures," said Michael Ryan, director of the WHO emergency program, at a conference press.

The United States announced on Thursday that it will end the mandatory use of facial masks for vaccinated people, including in some closed environments, due to the favourable evolution of the fight against the covid-19 pandemic, a change welcomed by President Joe Biden.

The Centers for Disease Control and Prevention (CDC) revised their guidelines for fully vaccinated people, allowing them to stop wearing masks outdoors in crowds and in most indoor environments.

However, the use of masks in crowded closed environments, such as buses, airplanes, hospitals or prisons, is still required.

At today's press conference, held digitally from the WHO headquarters in Geneva, Michael Ryan recalled that vaccines against covid-19 protect against the most serious disease, but there is still no “great proof of the ability to a vaccinated person infects other people ”.

In view of this, countries that intend to remove the obligation to wear a mask, should only do so "taking into account the intensity of transmission in this area and, at the same time, the level of vaccination coverage", said the WHO responsible for the programs emergency, without specifically referring to the United States.

For the epidemiologist Maria Van Kerkhove, technical responsible for the WHO response to covid-19, the decision of the national authorities on the waiver of the use of a mask must always be evaluated “within the context” of each country, but also on the level of vaccination achieved.

“We are not yet out of danger. There are still many uncertainties due to the variants and we must do everything possible to prevent further infections and save lives ”, warned the epidemiologist.