USA TODAY
Corrections & clarifications: This story has been updated to clarify the number of COVID-19 vaccine shots administered in the U.S.
The Centers for Disease Control and Prevention has had a busy week.
Only a few days after announcing updated mask guidelines, the agency on Friday released new scientific data on the delta variant that gives a snapshot of how the highly contagious strain triggered a wave of coronavirus cases.
In a briefing Tuesday, CDC director Dr. Rochelle Walensky said the new data spurred the agency to take immediate action by recommending fully vaccinated people to wear mask indoors in public settings where coronavirus transmission is high.