The number of deaths in the U.S. associated with COVID-19 exceeded 500,000 Sunday, according to a NBC News tally Monday.

Figures from Johns Hopkins University said more than 497,600 people had died. Another 91,000 are predicted to die by June 1, the University of Washington's Institute for Health Metrics and Evaluation said.

"Half a million deaths. It's just terrible. It's historic. We have not seen anything even close to this for well over a hundred years since the 1918 influenza pandemic," Dr. Anthony Fauci, chief of the National Institute of Allergy and Infectious Diseases, said during NBC's Meet the Press.

The Centers for Disease Control and Prevention projects a variant first detected in Europe might become the dominant U.S. strain by the end of March. Variants first discovered in Brazil and South Africa, both believed to be more resistant to vaccines, have also been reported in the U.S.

About 15% of the population has been given at least one dose, with almost 43 million receiving at least one shot and almost 18 million being administered with a second shot, according to Reuters, citing U.S. statistics.

The coronavirus has killed more than 2,462,000 people worldwide, according to data compiled by Johns Hopkins University. The toll in the U.S. is the highest in the world. It has about 5% of the world's population.

Fauci estimated that between 70% and 85% of the country's population needs to be immunized for herd immunity to take effect. He doesn't expect the U.S. will reach herd immunity before next winter.