Up to 90 percent of Americans may get the COVID-19 vaccine by the end of the pandemic, Dr. Eric Topol, the Scripps Research Translational Institute founder and director, said.

“Now we need 85 to 95% vaccinated against Delta,” Topol told USA Today.

The 90 percent number was also placed by the Rhode Island Department of Health COVID Response Unit Tom McCarthy, according to the report which cited the Delta variant.

In an interview released in December, the National Institute of Allergy and Infectious Diseases head Dr. Anthony Fauci said that between 70 to 90 percent of the population needs to get the COVID-19 vaccine in the U.S. for herd immunity to be achieved.

“We really don’t know what the real number is. I think the real range is somewhere between 70 to 90 percent. But, I’m not going to say 90 percent,” Fauci said in the interview.

Herd immunity happens when a huge percentage of a definite population builds immunity against a virus.

It can be achieved through vaccines or in a natural way to prevent infectious diseases like the COVID-19.

In the U.S., about 56 percent or 185 million are identified to get the complete vaccine doses.

On Sunday, Fauci suggested that Americans may celebrate Christmas on their own this year. In an interview with CBS’s “Face The Nation,” he said it is too early to tell, FOX News reported.

“We have to concentrate on continuing to get those numbers down and not try to jump ahead by weeks or months and say what we’re going to do at a particular time,” Fauci said.