The Omicron XBB.1.5 subvariant, which is spreading rapidly in the United States but still remains marginal in Quebec, is to date the most transmissible subvariant of the virus responsible for COVID-19 and threatens to become the dominant strain in Europe in the coming months. Here is what we know about him.
Where and what?
This subvariant was first detected in the United States in October and now accounts for more than 27% of the country’s infections, according to the Centers for Disease Control and Prevention’s (CDC) Variant Tracker.
A total of 38 countries have reported cases of XBB.1.5, including 82% in the United States, 8% in the United Kingdom and 2% in Denmark, the World Health Organization (WHO) said in an assessment on Wednesday. rapid risk.
In Quebec, it represented 2.4% of COVID-19 cases between December 25 and 31, according to the National Institute of Public Health of Quebec (INSPQ).
The European Center for Disease Prevention and Control (ECDC) said this week that XBB.1.5 currently accounts for only 2.5% of cases in Europe. But mathematical models from the European Union health agency, based on the growth rate of this subvariant, show that it could become the dominant strain in Europe within one to two months, a- she let know on Friday.
XBB.1.5 is very similar to its predecessor, XBB.1, but has an additional mutation of its spike protein, the famous key to the virus entering cells, Grace Roberts, a virologist at the British university, told AFP. of Leeds.
Contagion and gravity
It is the most transmissible subvariant to date, Maria Van Kerkhove, WHO technical lead on COVID-19, said this week. It clearly has a “growth advantage”.
The most likely explanation for this advantage is the spike protein mutation, which comes on top of a recombination of an already highly transmissible strain, the ECDC said.
In the United States, XBB.1.5 is currently spreading 12% faster than other variants in circulation, according to the ECDC.
However, “there is no data to suggest that XBB.1.5 is more harmful — in terms of serious illness and death — than previous variants,” said Dr. Grace Roberts. The WHO continues to evaluate the data but, for the moment, XBB.1.5 does not carry any mutations known to increase the severity of the disease, also judged the agency.
Antibody resistance
Omicron’s “XBB” sublines are, alongside BQ.1, the most resistant to antibodies accumulated from vaccination and previous infections, according to the WHO.
A study published in the journal Cell last month revealed that XBB.1 was thus 63 times less likely to be neutralized by existing antibodies than the Omicron BA.2 subvariant.
It is also 49 times stronger than the BA.4 and BA.5 subvariants, which are currently dominant in Quebec, the UK, and many other countries. However, new research has shown that bivalent COVID-19 vaccines can continue to be effective against XBB.1, according to US expert Eric Topol.
How worrisome is it?
ECDC said the overall risk level of the subvariant remains low for the general population. However, the risk is “moderate to high” for vulnerable people, such as the elderly or unvaccinated, he added, calling for more testing and vaccination.
There is “no reason to panic” about XBB.1.5, said Grace Roberts.
“I don’t think we need to take any drastic measures at the moment,” she said, while deeming it important to continue monitoring her progress.
The total number of COVID-19 cases worldwide fell 9% last week from the previous seven days and new deaths fell 12%, according to the WHO, a situation that comes after a rise seen in the during the vacation period.
“Kraken”
The WHO has decided not to name Omicron subvariants after the letters of the Greek alphabet. But on Twitter, he was given the disturbing nickname “Kraken”.
“I think it may cause unnecessary concern to associate a virus with a mythical giant sea creature! Reacted Grace Roberts.