Dr. Anthony Fauci says the highly-contagious Delta variant is now the greatest threat in the U.S. to eliminating the virus.
Research suggests vaccinations are effective against it. But the CDC director warns this variant could eventually lead to worse mutations of COVID if it's not stopped.
Dr. Rochelle Walensky says, "it's more important than ever to get vaccinated now to stop the chain of infection, the chain of mutations that could lead to a more dangerous variant."
