Dr. Anthony Fauci had previously said it could take up to 90% of the US population to get vaccinated to reach herd immunity against the coronavirus.
But on Sunday, he clarified his 'guesstimate' downwards to 70 to 85% of the population.
Business Insider reports Fauci admitted on CNN's 'State of the Union' that 'we all have to be honest and humble, nobody really knows for sure.'
This month, the US Food and Drug Administration authorized both Moderna and Pfizer and BioNTech's coronavirus vaccine for emergency use.
Healthcare professionals and frontline workers across the country have been getting vaccinations since the vaccine rollouts.
