Why is the mask being advised again even after vaccination?
Do we still have to put on masks? Even if we are vaccinated? For much of the United States, this is the latest advice from the Centers for Disease Control and Prevention (CDC).
The CDC has updated its mask guidelines this week to curb the spread of the coronavirus.
The change comes just two months after the CDC found that fully vaccinated people no longer needed to wear masks indoors.
Since then, the agency has also said that vaccinated adults and teens do not need to wear masks even in camps or summer schools.
CDC officials have announced that people who are fully vaccinated should return to wearing masks indoors if they live in areas where coronavirus infection is on the rise. These areas currently make up the bulk of the U.S., or more than 60% of U.S. counties. Masks, in general, are not needed outside.
The agency has also said that all teachers and students should wear masks in schools, regardless of whether the coronavirus is on the rise in the community or not.
The CDC was not the first to call for the return of the masks. In recent weeks, several American cities have introduced rules for wearing masks indoors.
It's all because of the more contagious version of the coronavirus, Delta, the CDC has said.
This variant is driving the increase in the number of cases in most of the US and now accounts for more than 80% of infections.
CDC officials have said that new information about its spread has forced them to change their approach.
The vast majority of new infections in the US continue to be among unvaccinated people.
Rarely, some vaccinated people end up as infected, although the vaccine soothes the stroke and generally protects against severe symptoms.
Previously, vaccinated and infected people had low levels of the virus and were less likely to spread it, said CDC director Rochelle Walensky.
But, new data show that this is not the case with the Delta variant. "Vaccinated people" have the potential to spread the virus to others, "she said.
The instructions for anyone who has not been vaccinated against coronavirus remain the same: Masks are recommended inside, almost everywhere.
Everyone - regardless of vaccination or location - must wear masks when at airports or train stations, or when entering buses, trains or other public transport.
Hospitals, shops and businesses may also require masks.
The CDC has not explicitly changed the summer camp guidelines because the season is coming to an end and schools will reopen soon.
The new guideline is for areas with significant or high prevalence of coronavirus, which the CDC shows through the map.
According to the CDC, the rate of new cases is particularly high in the south and southwest of the US.
And, rates are high in all counties except a few in Alabama, Mississippi and Missouri.