LONDON — The omicron Covid variant is likely to spread further and poses a “very high” global risk, according to the World Health Organization, which warned Monday that surges of Covid infections caused by the variant of concern could have “severe consequences” for some areas.

“Given mutations that may confer immune escape potential and possibly transmissibility advantage, the likelihood of potential further spread of Omicron at the global level is high,” the WHO said in its risk assessment on Monday within a technical brief to its 194 member states.

“Depending on these characteristics, there could be future surges of Covid-19, which could have severe consequences, depending on a number of factors including where surges may take place. The overall global risk related to the new VOC [variant of concern] Omicron is assessed as very high,” the U.N. health agency said.

The WHO designated the variant B.1.1.529, which was first spotted in South Africa, as a “variant of concern” last Friday.

It said in its report on Monday that it is “a highly divergent variant with a high number of mutations … some of which are concerning and may be associated with immune escape potential and higher transmissibility.”

However, there are still considerable uncertainties and unknowns regarding this variant, it said, repeating that sentiment on Monday.

First of all, experts don’t know yet just how transmissible the variant is and whether any increases are related to immune escape, intrinsic increased transmissibility, or both.

Secondly, there is uncertainty over how well vaccines protect against infection, transmission and clinical disease of different degrees of severity, and death. And third of all, there is uncertainty over whether the variant presents with a different severity profile.

The WHO has said it will take weeks to understand how the variant may affect diagnostics, therapeutics and vaccines. Preliminary evidence suggests the strain has an increased risk of reinfection, however.

Read more: A heavily mutated Covid variant emerges in southern Africa: Here’s what we know so far

Early data suggests the variant is spreading in South Africa more rapidly than previous variants did and that the variant could be starting to trigger a new wave of infections, according to an analysis by the Financial Times.

Covid symptoms linked to omicron have been described as “extremely mild” by the South African doctor who first raised the alarm over the new strain.

Read more: South African doctor who first spotted the omicron Covid variant explains the symptoms

It’s very important to remember that, so far, there have only been a small number of cases reported around the world — in several southern African countries and a smattering of cases in the U.K., France, Israel, Scotland, Belgium, the Netherlands, Germany, Italy, Australia, Canada and Hong Kong, but none yet in the U.S. — so it could take a while to fully understand what specific symptoms, if any, are attributable to the omicron variant on a wider scale.

It’s also too early to tell what degree of health risk the new variant poses at a global level; the international community has already seen several increasingly virulent strains of Covid-19, first with the “alpha” variant and then the “delta” variant, which is currently the globally dominant strain.

Covid vaccines have greatly helped to reduce severe infection, hospitalization and death, so new variants are closely monitored to assess whether, and how, they might impact the efficacy of vaccines.

The WHO urged member states to enhance surveillance and sequencing efforts to better understand variants, including omicron, and to increase community testing to detect if omicron is circulating in the community.

It also called on member states to accelerate Covid vaccinations “as rapidly as possible,” especially among high priority groups.

News of a new variant spooked global markets last Friday but European markets climbed on Monday morning. The region has already been battling with a sharp surge in infections caused by the delta variant, putting pressure on health services in a number of countries, including Germany and the Netherlands.

The WHO urged countries to put in place mitigation measures to prepare for a possible increase in Covid caseloads “and associated pressure on the health system, ensure mitigation plans are in place to maintain essential health services and necessary health care resources are in place to respond to potential surges.”