LONDON - An advisory panel of the World Health Organization classified a new COVID-19 variant first detected in South Africa as a highly transmissible virus of concern and named it "omicron" under its Greek-letter system.
The announcement Friday from the United Nations health agency marks the first time in months that WHO has classified a COVID-19 variant as such. The delta variant, which has become the world’s most prevalent, is in the same category.
Here's what we know so far:
WHAT IS THIS NEW COVID-19 VARIANT IN SOUTH AFRICA?
South African scientists have identified a new version of the coronavirus this week that they say is behind a recent spike in COVID-19 infections in Gauteng, the country’s most populous province. It's unclear where the new variant actually arose, but it was first detected by scientists in South Africa and has also been seen in travelers to Belgium, Botswana, Hong Kong and Israel.
Health Minister Joe Phaahla said the variant was linked to an "exponential rise" of cases in the last few days, although experts are still trying to determine if the new variant, named B.1.1.529, is actually responsible.
From just over 200 new confirmed cases per day in recent weeks, South Africa saw the number of new daily cases rocket to 2,465 on Thursday. Struggling to explain the sudden rise in cases, scientists studied virus samples from the outbreak and discovered the new variant.
On Friday, the World Health Organization was convening a group of experts to assess the data from South Africa.
WHY ARE SCIENTISTS WORRIED ABOUT THIS NEW VARIANT?
It appears to have a high number of mutations — about 30 — in the coronavirus’ spike protein, which could affect how easily it spreads to people.
Sharon Peacock, who has led genetic sequencing of COVID-19 in Britain at the University of Cambridge, said the data so far suggest the new variant has mutations "consistent with enhanced transmissibility," but said that "the significance of many of the mutations is still not known."
Lawrence Young, a virologist at the University of Warwick, described the variant as "the most heavily mutated version of the virus we have seen." He said it was concerning that although the variant was only being detected in low levels in parts of South Africa, "it looks like it's spreading rapidly."
Dr. Anthony Fauci, the U.S.' top infectious diseases doctor, said American officials had arranged a call with their South African counterparts later on Friday to find out more details and said there was no indication the variant had yet arrived in the U.S.
WHAT'S KNOWN AND NOT KNOWN ABOUT THE VARIANT?
Scientists know that the new variant is genetically distinct from previous variants including the beta and delta variants, but do not know if these genetic changes make it any more transmissible or dangerous.
South African scientists have noticed a surge of cases, but don't know if the new variant is responsible. It will take weeks to sort out if vaccines are still effective against it.
So far, there is no indication the variant causes more severe disease. South African experts said that as with other variants, some infected people don’t have any symptoms.
Even though some of the genetic changes in the new variant appear worrying, it's still unclear if the virus will pose a significant public health threat. Some previous variants, like the beta variant, initially concerned scientists but didn't end up spreading very far.
Francois Balloux, director of the Genetics Institute at University College London said it was impossible to make any predictions about whether or not the virus was more dangerous or infectious based on its genetic make-up alone.
HOW DID THIS NEW VARIANT ARISE?
The coronavirus mutates as it spreads and many new variants, including those with worrying genetic changes, often just die out. Scientists monitor COVID-19 sequences for mutations that could make the disease more transmissible or deadly, but they cannot determine that simply by looking at the virus. They must compare the pattern of disease in outbreaks to the genetic sequences. Determining whether there is an actual connection can take time.
Peacock said the variant "may have evolved in someone who was infected but could then not clear the virus, giving the virus the chance to genetically evolve," in a scenario similar to how experts think the alpha variant — which was first identified in England — also emerged, by mutating in an immune-compromised person.
ARE THE TRAVEL RESTRICTIONS BEING IMPOSED BY SOME COUNTRIES JUSTIFIED?
Maybe. As of noon Friday, travelers arriving in the U.K. from South Africa, Namibia, Botswana, Lesotho, Eswatini and Zimbabwe will have to self-isolate for 10 days. European Union nations also moved quickly on Friday to try to stop air travel from southern Africa.
Given the recent rapid rise in COVID-19 in South Africa, restricting travel from the region is "prudent," said Neil Ferguson, an infectious diseases expert at Imperial College London.
Balloux of University College London said that if the new variant turns out to be more infectious than delta, the new restrictions will have little impact but that they could still buy the U.K. some time to boost vaccination rates and roll out other possible interventions.
WHAT HAPPENS NEXT?
The discovery of a new coronavirus variant sent a chill through much of the world Friday as nations raced to halt air travel, markets fell sharply and scientists held emergency meetings to weigh the exact risks, which were largely unknown.
A World Health Organization panel named the variant "omicron" and classified it as a highly transmissible virus of concern, the same category that includes the delta variant, the world's most prevalent. The panel said early evidence suggests an increased risk of reinfection.
Variants of interest — which currently include the mu and lambda variants — have genetic changes known to affect things like transmissibility and disease severity and have been identified to cause significant clusters in multiple countries.
Variants of concern — which include alpha, beta and delta — have shown they can spread more easily, cause more serious disease or make current tools like vaccines less effective.
To date, the delta variant remains by far the most transmissible form of COVID; it accounts for more than 99% of sequences shared with the world's biggest public database.
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