XBB.1 is 63 times less likely to be neutralized by existing antibodies. (agent)
Paris:
The Omicron subvariant XBB.1.5, the most transmissible COVID-19 subvariant to date, is spreading rapidly across the United States and was predicted on Friday to become Europe’s dominant strain within weeks.
Here’s what we know about XBB.1.5.
where and what
The subvariant was first detected in the US in October and now represents more than 27 percent of the country’s infections, according to the CDC’s variant tracker.
Thirty-eight countries have reported XBB.1.5 cases, with 82 percent in the US, eight percent in Britain and two percent in Denmark, the World Health Organization said in a rapid risk assessment on Wednesday.
The European Center for Disease Prevention and Control (ECDC) said on Friday that its model suggests that XBB.1.5 could become the dominant strain in Europe in a month or two.
The agency said the increase would reflect the current low level of XBB.1.5 — it currently accounts for only 2.5 percent of European cases — and its projected growth rate.
The subvariant is similar to its predecessor XBB.1, but has an additional mutation in its spike protein – the key that allows the virus into the body’s cells – said Grace Roberts, a virologist at the University of Leeds in the UK.
Infectiousness and Severity
Maria Van Kerkhove, WHO’s technical lead on Covid, said this week that XBB.1.5 was the most transmissible form of Covid and clearly had an “evolution advantage” over other forms of the virus.
According to the ECDC, the subvariant is currently spreading 12.5 percent faster in the US than the other variants.
But Roberts told AFP, “There is no data to suggest that XBB.1.5 is more harmful than previous variants in terms of severe disease and death.”
The WHO is still assessing the data on this topic but said that there are no mutations in XBB.1.5 that are known to increase the severity.
resistance to antibodies
According to the WHO, the XBB variant of Omicron, along with BQ.1, are most resistant to antibodies produced from vaccination and previous infections.
A study published last month in the journal Cell found that XBB.1 is 63 times less likely to be neutralized by existing antibodies than the BA.2 subvariant.
It is 49 times more resistant than the BA.4 and BA.5 subvariants, which are currently dominant in the UK and many other countries.
Roberts pointed to a recent preprint study, which has not been peer-reviewed, that suggests XBB.1.5 has similar antibody resistance to XBB.1, but is more transmissible.
But “it’s important to remember that antibodies are only one part of our immune system,” she said.
US expert Eric Topol said the new research suggested that bivalent Covid vaccines targeting the BA.5 subvariant were also more effective in neutralizing the antibody response to XBB.1.5 than previous jabs.
This is because “the spike protein of the BA.5 bivalent more closely resembles XBB.1.5 than the Wuhan ancestral spike,” Topol wrote this week on Substack.
Regarding how?
The ECDC stated that the overall risk level of the subvariants remains low for the general population.
However, if the risk is moderate to high, such as for the elderly or non-vaccinated vulnerable people, it calls for more testing and to ramp up vaccination.
Roberts said that there is “nothing to panic” about XBB.1.5.
“I don’t think we need to take any drastic action at present,” she said, adding that it is important for countries to monitor the progress of the subvariant.
According to the World Health Organisation, the total number of Covid cases worldwide declined by nine per cent in the past week compared to the previous seven days, while deaths fell by 12 per cent, following an extended holiday period.
‘Kraken’
Unlike the major variants, the WHO has decided not to name any of the omicron subvariants after letters of the Greek alphabet, as yet most are similar in transmissibility and severity.
But Twitter users are informally giving different subvariants nicknames based on the mythology, with XBB.1.5 being called “Kraken,” Roberts said.
“I personally think this may cause unnecessary worry – especially naming viruses after mythical giant sea creatures!” she added.
(Except for the headline, this story has not been edited by NDTV staff and is published from a syndicated feed.)
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