The World Health Organization said Monday in a new risk assessment that it believes the COVID-19 Omicron variant poses a "very high" risk to the globe because it may be more transmissible than other strains of the virus.

Why it matters: Though the WHO acknowledged there are still many uncertainties associated with the variant, the agency said it believes the likelihood of potential further spread of Omicron around the world is "high."

• The health agency warned that the variant could potentially drive future COVID-19 surges that strain health care systems, especially in countries with low vaccination rates.
• It's still uncertain how transmissible the variant is, how effective vaccines are against it or whether it causes more severe illnesses and a higher risk of death.
• Scientists and health officials in South Africa, where Omicron was first detected, said the new variant appears to be more transmissible than others but added that observed cases have so far been mild.

What they're saying: "The overall global risk related to the new [variant of concern] Omicron is assessed as very high," the WHO said.

• "Increasing cases, regardless of a change in severity, may pose overwhelming demands on health care systems and may lead to increased morbidity and mortality," it added.
• "The impact on vulnerable populations would be substantial, particularly in countries with low vaccination coverage."
• Currently, no deaths associated with the Omicron variant have been reported, the WHO said.

The big picture: Despite Omicron's designation as a variant of concern, the WHO has criticized travel bans on southern African nations by the U.S. and European and Asian countries, saying they may "slightly" reduce the spread of COVID-19 but will "place a heavy burden on lives and livelihoods."

Go deeper: First North American Omicron cases identified in Canada