Sixty-one people who traveled from South Africa to the Netherlands have tested positive for COVID-19 and will be tested for the newly discovered COVID variant omicron, The Associated Press reported.

Two flights from Johannesburg and Cape Town arrived in the Netherlands Friday, just after the Dutch government, along with other countries, imposed a ban on southern African nations with the discovery of omicron, according to the AP.

Those who tested positive must remain in quarantine for seven days if they have symptoms and five days if they do not.

-ABC News' Ahmad Hemingway

The Centers for Disease Control and Prevention said in a statement Friday that it is "following the details of this new variant," omicron, first reported to the World Health Organization by South Africa.

"We are grateful to the South African government and its scientists who have openly communicated with the global scientific community and continue to share information about this variant with the U.S. Department of Health and Human Services and CDC," the CDC said, adding that it is continuing to learn more about the variant and monitor its path.

No cases of omicron have been identified in the U.S. to date, but on Friday the WHO classified the new variant as a "variant of concern.”

"CDC is continuously monitoring variants and the U.S. variant surveillance system has reliably detected new variants in this country," the CDC said. "We expect Omicron to be identified quickly, if it emerges in the U.S."

The CDC recommends that people traveling to the U.S. continue to follow its guidance for traveling.

Moderna on Friday announced that it is testing three existing COVID-19 vaccine booster candidates to address the newly named omicron variant.

Data on the ability of the current vaccine dose to neutralize the new variant should be available in the coming weeks, the company said in a statement.

Moderna also said the company has been testing variant-specific boosters and is “working rapidly” to advance an omicron-specific booster candidate.

“The mutations in the omicron variant are concerning, and for several days, we have been moving as fast as possible to execute our strategy to address this variant,” Chief Executive Officer Stéphane Bancel said.

The U.S. will be restricting entry for foreign nationals from southern African countries in response to the discovery of omicron, the new COVID-19 variant, said senior administration officials.

According to officials, President Joe Biden will restrict travel from South Africa, Botswana, Zimbabwe, Namibia, Lesotho, Eswatini, Mozambique and Malawi.

They take effect Nov. 29 and will not apply to American citizens or lawful permanent residents.

In a statement released Friday, Biden urged Americans to get vaccinated and called upon other nations to increase vaccine donations and "match America's speed and generosity."

"Finally, for the world community: The news about this new variant should make clearer than ever why this pandemic will not end until we have global vaccinations," Biden said.

Canada and the United Kingdom announced a similar ban on Friday and Thursday, respectively.