Dr. Anthony Fauci, right, testifies before a House appropriations subcommittees hearing on Wednesday, March 4. Olivier Douliery/AFP/Getty Images

Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, said the mortality rate for novel coronavirus is about 2% if "you just do the math."

"If you look at the cases that have come to the attention of the medical authorities in China, and you just do the math, the math is about 2%. If you look at certain age groups, certain risk groups, the fatality is much higher. But as a group it’s going to depend completely on what the factor of asymptotic cases are. So if you have asymptotic cases that are a lot, it's going to come down,” Fauci said on Wednesday during a House Appropriations Committee hearing on NIH's budget.

On Tuesday, World Health Organization Director-General Tedros Adhanom Ghebreyesus said globally the rate is about 3.4%.

Speaking about the WHO’s higher number, Fauci said, “What we're hearing right now, on a recent call from the WHO this morning is that there aren't as many asymptotic cases as we think. Which made them elevate, I think, what their mortality is.”

Fauci warned, “You know as well as anybody that the mortality for seasonal flu is .1% so even if it goes down to 1% it's still 10 times more fatal."