On Tuesday, CDC Director Dr. Rochelle Walensky said that children and teachers should all be wearing face coverings when they return to school in the fall.
Whether they're vaccinated or not, all Americans living in locations where coronavirus transmission is either "substantial" or "high" should wear masks in indoor settings, according to Walensky. That currently applies to about 63.45 percent of US counties.
The u-turn was made despite data from other countries such as the UK showing the delta variant to cause a brief rise in cases before quickly falling without the need for more draconian mask mandates.
Donald Trump savaged the reintroduction of mask mandates and and basically urged Americans to ignore them.
"We won't go back. We won't mask our children. Joe Biden and his Administration learned nothing from the last year," said Trump.
"Brave Americans learned how to safely and responsibly live and fight back. Don't surrender to COVID. Don't go back! Why do Democrats distrust the science? Don't let this happen to our children or our Country," he added.