Dr. Anthony Fauci, the director of the National Institute of Allergy and chief medical advisor to President Joe Biden, provided another stern warning in relation to the spread of the delta COVID-19 variant on Thursday (August 5) morning.

During an appearance on Good Morning America, Dr. Fauci told anchor George Stephanopoulos the U.S. could see more variants of the coronavirus evade the protection of vaccines if it does not get the spread of the delta variant under control.

"That will happen, George, if we don't get good control over the community spread which is the reason why I and my colleagues keep saying and over again, it is very important to get as many people vaccinated as we possibly can," Fauci said via ABC News. "People who say, 'I don't want to get vaccinated because it's me and I'll worry about me, I'm not having any impact on anybody else,' that's just not the case."

The delta variant is reported to be "highly contagious, likely to be more serve" than previous known strains of the coronavirus and that “breakthrough infections may be as transmissible as unvaccinated cases,” according to the CDC.

"And when you give it ample opportunity to mutate, you may sooner or later get another variant, and it is possible that that variant might be in some respects worse than the already very difficult variant we're dealing with now, which is a major reason why you want to completely suppress the circulation of the virus in the community," Fauci added during Thursday's Good Morning America appearance.

On Sunday (August 1), Dr. Fauci told ABC's This Week he didn't think the country would be forced to go back into lockdowns similar to the beginning of the ongoing COVID-19 pandemic, but warned "things will get worse" than they currently are.

"I don't think we're gonna see lockdowns. I think we have enough of the percentage of people in the country -- not enough to crush the outbreak -- but I believe enough to not allow us to get into the situation we were in last winter. But things are going to get worse," Dr. Fauci told This Week co-host Jonathan Karl. "If you look at the acceleration of the number of cases, the seven-day average has gone up substantially. You know what we really need to do, Jon, we say it over and over again and it's the truth -- we have 100 million people in this country who are eligible to be vaccinated who are not getting vaccinated. We are seeing an outbreak of the unvaccinated."

"From the standpoint of illness, hospitalization, suffering and death, the unvaccinated are much more vulnerable because the vaccinated are protected from severe illness, for the most part, but when you look at the country as a whole. And getting us back to normal, the unvaccinated, by not being vaccinated, are allowing the propagation and the spread of the outbreak which ultimately impacts everybody," Fauci said.

The CDC reports more than 70% of the adult U.S. population has received at least one dose of the coronavirus vaccine and 60.7% are fully vaccinated, while 67.9% all eligible Americans -- ages 13 and older -- have had at least one dose and 58.3% are fully vaccinated.

However, numerous U.S. states are reporting vaccination rates well below the national average, and there are still about 93 million individuals eligible who have not gotten vaccinated as of Thursday.