Fauci names new COVID-19 variant health officials are ‘keeping an eye on’

Dr. Anthony Fauci, the top disease expert in the U.S., said in an interview Sunday that health officials are keeping an eye on the COVID-19 Mu variant to see if it emerges to become more dominant.

He said the Delta variant makes up for over 99% of the cases in the U.S. The Mu variant has mutations that "indicate that it might evade the protection from certain antibodies."

RELATED: COVID-19 ‘mu’ strain: WHO tracks latest ‘variant of interest’

Earlier this week, mu, known by scientists as B.1.621, was added to the World Health Organization’s (WHO) "of interest" list of variants. The variant was first identified in Colombia and has been confirmed in at least 39 countries, according to the WHO.

He said the Mu variant is "not an immediate threat."

The U.S. is projected to see nearly 100,000 more COVID-19 deaths between now and Dec. 1, according to the nation’s most closely watched forecasting model. But health experts say that toll could be cut in half if nearly everyone wore a mask in public spaces.

"Behavior is really going to determine if, when and how sustainably the current wave subsides," said Lauren Ancel Meyers, director of the University of Texas COVID-19 Modeling Consortium. "We cannot stop delta in its tracks, but we can change our behavior overnight."

Fox News' Peter Aitken and the Associated Press contributed to this report.