The World Health Organization advised people over 60 years old and those with underlying conditions to postpone travel plans as the world tries to understand the Omicron coronavirus variant.

The WHO noted that the variant (B.1.1.529) has been reported in several countries and is expected to spread.

While the WHO said not everything is understood about the Omicron variant, which the agency dubbed a "variant of concern," the variant raised red flags after initial data suggested its mutations might make it more likely for someone to be reinfected with COVID-19.

"WHO is closely monitoring the spread of the Omicron variant, and studies are ongoing to understand more about these mutations and their impact on transmissibility, virulence, diagnostics, therapeutics, and vaccines," the organization said in a press release.

They also said people who are are unwell, or who have not been fully vaccinated against COVID-19 should exercise caution while traveling.

While the WHO issued caution for those with increased risk of developing severe symptoms of COVID-19, the agency said "blanket travel bans" will "not prevent the international spread, and they place a heavy burden on lives and livelihoods."

The organization encouraged all travelers to remain vigilant for symptoms, adhere to public health measures, and get vaccinated.