This browser does not support the Video element.
LOS ANGELES - The World Health Organization is advising elderly travelers as well as individuals who are vulnerable to COVID-19 to rethink their travel plans amid the spread of the new omicron coronavirus variant.
On Tuesday, the WHO advised individuals who are 60 years of age and older — including those who are vaccinated — as well as those with compromised immune systems to postpone upcoming holiday travel and specifically avoid areas with significant community transmission of the virus.
RELATED: First U.S. case of omicron COVID-19 variant detected in California
"All travellers should be reminded to remain vigilant for signs and symptoms of COVID-19, to get vaccinated when it is their turn and to adhere to public health and social measures at all times and regardless of vaccination status, including by using masks appropriately, respecting physical distancing, following good respiratory etiquette and avoiding crowded and poorly ventilated spaces," the WHO wrote.
The WHO is also calling on all nations to implement travel-related risk mitigation measures in order to control potential outbreaks of the omicron variant. But the organization said "blanket travel bans" will not prevent the international spread of the disease, and more elaborate planning is needed to contain the virus.
Recommended measures include sharing contact tracing information, enhanced scientific surveillance and sequencing efforts in order to better understand how the disease spreads and continued performance of laboratory assessments to predict potential impacts of the virus.
"These measures, nonetheless, need to be defined following a thorough risk assessment process informed by the local epidemiology in departure and destination countries and by the health system and public health capacities in the countries of departure, transit and arrival. All measures should be commensurate with the risk, time-limited and applied with respect to travellers’ dignity, human rights and fundamental freedoms," the WHO wrote.
On Nov. 26, a World Health Organization panel named the latest coronavirus variant "omicron" and classified it as a highly transmissible strain of concern, the same category that includes the predominant delta variant — which is still a scourge driving higher cases of sickness and death in Europe and parts of the United States.
In the U.S., health officials are requiring airlines to gather contact-tracing information on passengers heading to the U.S. who have been in southern Africa in the previous two weeks.
The U.S. Centers for Disease Control and Prevention said Wednesday that it issued the latest requirement "to prevent the importation and spread of a communicable disease of public health importance."
The directive follows President Joe Biden’s order that bars most foreign nationals from entering the U.S. if they have been in southern Africa, where the omicron variant of COVID-19 was first reported. The ban does not apply to American citizens or permanent U.S. residents who have been in those countries, although they must show evidence of a negative test for COVID-19.
RELATED: Biden: Omicron variant ‘cause for concern’ but not panic, pushes COVID-19 shots
Under the CDC order, which was obtained by The Associated Press, airlines will be required to keep information on those passengers for 30 days and give it to the CDC within 24 hours of a request by the health agency.
The U.S. recorded its first confirmed case of the omicron variant Wednesday — in a vaccinated traveler who returned to California after a trip to South Africa — as scientists around the world race to establish whether the new, mutant version of the coronavirus is more dangerous than previous ones.
This browser does not support the Video element.
Dr. Anthony Fauci, the United States’ top infectious-disease expert, announced the finding at the White House. "We knew it was just a matter of time before the first case of omicron would be detected in the United States," he said.
The infected person was identified as a traveler who had returned from South Africa on Nov. 22, developed mild symptoms and tested positive for COVID-19 Monday. Researchers at the University of California, San Francisco obtained a sample from the patient Tuesday evening and worked feverishly overnight to assemble the genetic sequence.
The person, who had had the full two doses of the Moderna vaccine and wasn't yet due for a booster shot, is improving, California officials said.
Fauci and other medical experts strongly emphasized that Americans should continue to get vaccinated and get their booster shots. The vaccine has been proven to reduce the risk of severe illness and death, and Fauci said it is reasonable to believe it will offer protection against the omicron variant.
The mild nature of the California person's infection "is a testimony to the importance of the vaccinations," said California Health Secretary Dr. Mark Ghaly.
All the individual’s close contacts have been reached and have tested negative, officials said. The patient, who agreed to remain in quarantine, was identified only as being between 18 and 49.
The Associated Press contributed to this story.