The US Centers for Disease Control and Prevention (CDC) has recommended that even vaccinated people in the country now have to wear masks while indoors, reversing a decision it made two months ago.
CDC made the announcement Tuesday, based on surging numbers of new cases in regions with low vaccination rates. The rising caseload is driven by the highly contagious delta variant of the coronavirus that causes Covid-19.
There has also been a rise in cases of so-called breakthrough infections among fully vaccinated people, suggesting the delta variant may be able to cause such infections more often than previous strains of the virus.
Health officials say vaccines remain effective against the worst outcomes of infection with the virus, including those involving the delta variant.
US infectious disease expert Anthony Fauci said they have not reversed the decision of wearing masks for everybody because the delta variant has 1,000 more times viral load among even the vaccinated people who can then go on to infect others.
"You don't get vaccinated because you don't want to wear a mask. If you don't wear a face mask you can innocently infect someone else. It goes beyond you," Fauci said. "We're not changing now, it is the virus changing...Vaccination will save your life from being hospitalised, even with the delta variant," he told CNN.
Earlier in May this year, the CDC said fully vaccinated people no longer would be required to wear masks or maintain social distancing of six feet from other people. The agency still suggested people remain masked on public transportation and at crowded outdoor events.
For months, Covid-19 cases, deaths and hospitalizations in the US fell steadily, but those trends reversed over the past two months as the delta variant of the coronavirus began to spread.
The New York Times reports several cities and towns have restored indoor masking rules in recent weeks, including St. Louis, Missouri, Savannah, Georgia and Provincetown, Massachusetts.