Anthony FauciAnthony FauciThe Hill's Morning Report - Presented by Alibaba - Government shutdown fears increase as leaders dig in Pfizer results offer hope amid worsening pandemic for children The Hill's Morning Report - Presented by Alibaba - Democrats return to disappointment on immigration MORE, President BidenJoe BidenUN meeting with US, France canceled over scheduling issue Schumer moves to break GOP blockade on Biden's State picks GOP Rep. Cawthorn likens vaccine mandates to 'modern-day segregation' MORE's chief medical adviser, on Sunday discussed new Centers for Disease Control and Prevention (CDC) data that showed the levels of coronavirus in breakthrough cases of the delta variant among those who are fully vaccinated are "almost identical" to the levels seen among unvaccinated individuals.
Appearing on CBS's "Face the Nation," Fauci stressed that the majority of breakthrough cases involving the delta variant saw "minimal symptoms or no symptoms at all."
Guest host John Dickerson asked Fauci what the CDC's reasoning was for recommending masks be worn by both vaccinated and unvaccinated people indoors.
"What we learned that's new, John, in answer to your question, is that when you look at the level of virus in the nasopharynx of people who are vaccinated who get breakthrough infections, it's really quite high and equivalent to the level of virus in the nasopharynx of unvaccinated people who get infected," Fauci said.
The nasopharynx is part of the nasal cavity located above the back of the throat. Fauci stated that it was "troubling" to find that the level of virus from the delta variant in both vaccinated and unvaccinated people is "really quite similar, almost identical."
According to Fauci, these findings differ from what was observed in cases involving the previously dominant alpha variant.
"So we know now that vaccinated people who get breakthrough infections can spread the virus to other people," Fauci said. "The fundamental basis for the CDC modifying their guidelines and saying now, 'If you're an area of a high or substantial trend of level of virus, namely a red or an orange zone, when you're in an indoor public setting, you need to wear a mask.' That's the fundamental reason for that change."