Senior administration officials said on Friday that it would be impossible to prevent a new variant of the coronaviruses from entering the United States.
The administration will prohibit travelers from South Africa, Zimbabwe, and other countries from coming to the United States.
The travel ban will not apply to American citizens. They will need to show a negative coronaviruses test before they can come to the US.
The decision was made by Mr. Biden after he was briefed by his advisers.
The White House made the decision after the World Health Organization said that the new version of the virus, called Omicron, was a variant of concern.
Mr. Biden told reporters that they were going to be cautious. The variant seems to spread quickly and we don't know a lot about it.
The travel restrictions will not stop the virus from coming to the US, experts said. It can give health officials and pharmaceutical companies time to determine if the current vaccines work against the new variant.
Dr. Fauci said that it would buy them some time. It isn't going to be possible to keep this disease out of the country. Can you slow it down?
Dr. Fauci said that the new variant has about 30 changes and 10 of them are on a part of the virus that is associated with immune protection. That suggests the virus may be more transmissible and may escape the current vaccines to an extent yet to be determined.
He said there had been some breakthrough infections among those who had recovered from the Delta variant.
He said that scientists don't know the severity of the infections caused by the new variant. It is possible that it causes less severe disease.
He said, "You don't want to say don't worry, and you don't want to say you've got to worry yourself sick, because we're gathering information rapidly."
The Biden administration is working with health officials in other countries to learn more about the variant.
The chair of the department of medical ethics at the University of Pennsylvania and an adviser to the president said that restrictions on travel won't stop it from coming. It is inevitable that it will come here. The environment in which it comes may be different. We can change the environment.
Mr. Biden and Dr. Fauci both said that the rise of the Omicron variant was a reason for unvaccinated Americans to get boosters. The international community should donate more vaccines to nations that suffer from a lack of access or poor vaccination rates, according to Mr. Biden.
The administration had little choice but to implement the travel ban, according to an infectious disease expert who advised Mr. Biden during his transition.
It could take time before scientists know if the current vaccines are effective against the variant and how transmissible it is. Lab studies will take several weeks to figure that out. It could take months to follow breakthrough cases in people who are already vaccine free.
