What we know about the new coronavirus variant omicron

Authorities around the world have reacted with alarm to the recently discovered coronavirus variant B.1.1.529 that the World Health Organization labelled a variant of concern and named omicron Friday. 

Canada, the U.S., Britain, the European Union and India are among those announcing stricter border controls as scientists carry out tests to determine if the variant is more transmissible or infectious than others, as well as if it is resistant to vaccines.

South African scientists doing genomic sequencing detected the new variant on Tuesday in samples from Nov. 14-16. 

On Wednesday, South African scientists sequenced more genomes, informed the government that they were concerned and asked the World Health Organization (WHO) to convene its technical working group on virus evolution Friday.

The country has identified around 100 cases of the variant, mostly from its most populated province, Gauteng, where Johannesburg and Pretoria are located.

The UN agency said on Friday its advisers recommended that the variant be designated one of concern, its most serious level.

The latter label is applied if there is evidence that it is more contagious or more virulent or vaccines work less well against it, or has a combination of those characteristics, WHO's website says.

It has been given the Greek name omicron. WHO has identified four other variants "of concern" — alpha, beta, gamma and delta.

All viruses — including SARS-CoV-2, the virus that causes COVID-19 — change over time. Most changes have little or no impact on their properties.

However, some changes may affect how easily they spread, their severity or the performance of vaccines against them.

This variant has drawn scrutiny because it has more than 30 mutations of the spike protein that viruses use to get into human cells, U.K. health officials say.

That is about double the number of delta, and makes this variant substantially different from the original coronavirus that current COVID vaccines were designed to counteract.

South African scientists say some of the mutations are associated with resistance to neutralizing antibodies and enhanced transmissibility, but others are not well understood, so its full significance is not yet clear.

U.K. Health Security Agency Chief Medical Adviser Dr. Susan Hopkins told BBC radio some mutations had not been seen before, so it was not known how they would interact with the other ones, making it the most complex variant seen so far.