The United States is facing a COVID-19 summer surge as the delta variant spreads.

More than 611,000 Americans have died from COVID-19, according to real-time data compiled by the Center for Systems Science and Engineering at Johns Hopkins University.

Just 57.6 percent of Americans ages 12 and up are fully vaccinated, according to data from the Centers for Disease Control and Prevention.

The Centers for Disease Control and Prevention on Tuesday, citing new science on the transmissibility of the delta variant, changed its mask guidance to now recommend everyone in areas with substantial or high levels of transmission vaccinated or not wear a mask in public, indoor settings.

The U.S. reported the highest number of new COVID-19 cases in the world in the last week, according to the World Health Organization. 

The U.S. saw a 131 percent increase in new cases for the week ending July 25 compared to the previous week, according to the WHO's epidemiological report.   

The U.S. was followed by Brazil, Indonesia, the United Kingdom and India.

(With input from agencies)