• The world is on high alert due to the new omicron Covid strain — but delta is still responsible for most of the current infections globally, the World Health Organization pointed out on Monday.
• Last week, the global health agency recognized the omicron variant, first referred to as lineage B.1.1.529, as a variant of concern.
• That means it could be more contagious, more virulent or more skilled at evading public health measures, vaccines and therapeutics.
• The omicron strain was first identified by South African scientists.

The world is on high alert due to the new omicron Covid strain — but delta is still responsible for most of the current infections globally, the World Health Organization pointed out on Monday.

"Over 99% of cases around the world are due to the delta variant and more deaths are occurring in the unvaccinated," WHO Chief Scientist Soumya Swaminathan told CNBC's "Squawk Box Asia" on Monday. "I think that's our priority while we wait to find out more about [the omicron] variant."

Last week, the global health agency recognized the omicron variant, first referred to as lineage B.1.1.529, as a variant of concern. That means it could be more contagious, more virulent or more skilled at evading public health measures, vaccines and therapeutics. The strain was first identified by South African scientists.

Delta, on the other hand, was first detected in India.

Why are health experts worried?

Health experts are concerned about the omicron variant's transmissibility given its unusual constellation of mutations and profile that differs from previous variants of concern.

"The profile of the mutations strongly suggest that it's going to have an advantage in transmissibility and that it might evade immune protection that you would get, for example, from a monoclonal antibody or from the convalescent serum after a person's been infected, and possibly even against some of the vaccine-induced antibodies," U.S. infectious disease expert Dr. Anthony Fauci told NBC's "Meet the Press" on Sunday.

"So it's not necessarily that that's going to happen, but it's a strong indication that we really need to be prepared for that," Fauci added.

WHO's Swaminathan told CNBC that scientists need time to conduct experiments and collect data that would help them answer some of the fundamental questions surrounding the new variant.

"What we would like to know is, is this variant more transmissible, even more than delta? We would like to know if there is a different clinical pattern, is it less severe, more severe when it causes disease?" she said, adding, "And thirdly, and very importantly, is this variant able to evade immune responses either after natural infection or after vaccines."

She also called on countries where the omicron variant has been detected to share their clinical data and genomic sequence data through WHO's platforms for scientists to study.

How fast is the variant spreading?

The omicron variant has now been detected in multiple places, including the United Kingdom, Israel, Belgium, Germany, Italy, Hong Kong, the Netherlands, Denmark, and Australia. Many countries have stepped up restrictions on travel from southern Africa to try and contain the spread of the new strain.

Covid vaccine makers Pfizer, BioNTech, Moderna, Johnson & Johnson and AstraZeneca said they are investigating and testing the omicron variant.

WHO's Swaminathan said that for the moment, it should be assumed that the existing vaccines will provide some protection, if not full protection against the new strain.

"It's really important that everybody out there who's still unvaccinated, or who has received only one dose, must get a full course of vaccination," she said.

"I think we still have a huge number of people around the world who haven't had their first course of vaccines and we also know that at the moment, it's the delta variant that's the major cause of the pandemic around the world," Swaminathan added.

Information compiled by Our World In Data showed around 43% of the world population has been fully vaccinated against Covid-19. But only a small percentage of people in low-income countries have received at least one dose.

The WHO has repeatedly criticized global vaccine inequity as most shots have been administered in affluent or middle-income countries, including booster doses.