A storefront sign as seen on July 19, 2021 in Los Angeles, California. (Photo by FREDERIC J. BROWN/AFP via Getty Images)

A storefront sign as seen on July 19, 2021 in Los Angeles, California. (Photo by FREDERIC J. BROWN/AFP via Getty Images)

(CNSNews.com) – “Something has changed,” Dr. Anthony Fauci said on Tuesday, in the weeks since May 13, when the CDC told Americans that “fully vaccinated people no longer need to wear a mask.”

“And what has changed is the virus,” Fauci said. “The CDC hasn’t changed, and the CDC hasn’t really flip-flopped at all.”

On Tuesday, the CDC did change its guidance, recommending that fully vaccinated people should resume wearing a mask in public, indoor settings in areas of substantial or high transmission, which is most of the country.

Fauci told MSNBC’s “Morning Joe” on Wednesday:

What’s happened is when the earlier recommendation was made, we were dealing predominantly with the alpha variant. And the alpha variant, when you look at individuals who are vaccinated, that the level of virus in the nasopharynx of vaccinated people who might get a breakthrough infection, that the level was low, indicating that it was extremely unlikely that a vaccinated person that happened to get infected — and that happens because the vaccine is certainly not 100 percent effective — that that would be very unlikely that they would transmit.

However, now we are dealing with the delta variant, which is really quite a lot more transmissible than the alpha variant, number one.

Number two, the data are clear, the most recent data, that when a person gets infected who has been vaccinated, namely a breakthrough infection, and they get infected with the delta variant, that the level of virus in their nasopharynx is about a thousand times higher than with the alpha variant, and it’s been well documented, that even though it’s a rare occurrence, those individuals can and have transmitted the virus to uninfected individuals.

And for that reason, the recommendations and the guidelines have been changed to say that if you are vaccinated, even though you are vaccinated, when you are in an indoor public setting in an area of the country with a high degree of viral dynamics, namely the red and orange sections on the CDC chart, then you need to wear a mask, even though you are vaccinated.

Fauci said the new guidance is intended to “protect the people who are vulnerable that you might inadvertently and innocently come into contact with.”

I mean, you don’t want anyone to get infected. If you’re not infected, you’re not going to transmit it to someone else. So, point number one, to protect you from getting infected.

The fact that you’re vaccinated, as we know, it is extremely unlikely that you’re going to get a hospitalization or die. Because people who are fully vaccinated, when they get a breakthrough infection, it is extremely unusual that they will get a serious outcome.

However, if you have the virus in nasopharynx, and you go home and have in your home, or with your acquaintances, people who are vulnerable, people who have immune-suppression, some of the very elderly, frail people whose immune response might not be robust and even unvaccinated children — so it’s a combination, you protect yourself; more importantly, you don’t want to inadvertently bring it back to your home or to another place where you could transmit it to someone else. That’s the reason for the mask-wearing mandate.

House Minority Leader Kevin McCarthy scoffed at the CDC’s latest mask guidance:

“Make no mistake,” McCarthy tweeted. “The threat of bringing masks back is not a decision based on science, but a decision conjured up by liberal government officials who want to continue to live in a perpetual pandemic state.”