Washington, United States: The Centers for Disease Control and Prevention in its revised mask guidance issued on Tuesday recommended that fully vaccinated people should resume wearing masks indoors again in places with high Covid-19 transmission rates. The agency is also recommending kids wear masks in schools this fall.
Centers for Disease Control and Prevention director Rochelle Walensky relayed the mask decision in a press call, citing new data that shows that while vaccines remain highly effective, rare breakthrough cases involving Delta have an increased risk of onward transmission.
"In areas with substantial and high transmission, CDC recommends fully vaccinated people wear masks in public indoor settings," she said.
According to the latest CDC data, much of the southern United States is experiencing high or substantial transmission, while highly vaccinated parts of the Northeast are mostly experiencing moderate rates of community transmission.
Following the move, President Joe Biden said that the revised guidelines showed that America needs to "do better" on vaccinations, adding that a mandate for the country's more than two million federal workers was now "under consideration."
He also said that he would lay out new steps on Thursday to overcome a lag in vaccinations, which have stalled badly for months despite the fact the United States has the highest supply of any country.
In a separate address to the US intelligence community, when asked about a possible vaccine mandate for US federal workers, Biden replied: "That's under consideration right now."
Walensky stressed that so-called "breakthrough" cases among people who are vaccinated remain rare -- authorized shots reduce the risk of symptomatic disease seven-fold, and hospitalizations and deaths by a factor of twenty.
However, new CDC research showed that when a vaccinated person does become infected, their viral load is similar to an unvaccinated person.
"That leads us to believe that the breakthrough infections, rare as they are, have the potential to forward transmit at the same capacity of an unvaccinated person."
As recently as last week, the CDC defended its May decision that vaccinated people do not have to wear masks indoors in most circumstances, with exceptions including public transit and hospitals.
But infection numbers are now swelling, thanks to the Delta variant, which accounts for around 90 percent of cases.
The latest seven day average of daily cases is more than 56,000, similar to levels last seen in April.
Forty-nine percent of the US population is fully vaccinated, but the vaccination rate is heavily skewed between politically liberal and conservative parts of the country.