XBB.1.5 strain, January 4, 2023, Suqian, Jiangsu, China.
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According to the World Health Organisation, the XBB.1.5 Omicron subvariant that currently dominates the US is the most infectious variant of COVID-19 yet, but it does not make people sick.
Maria Van Kerkhove, WHO’s COVID-19 technical lead, said global health officials are concerned about how quickly the subvariant is spreading in the northeastern Americas. The number of people infected with XBB.1.5 is doubling every two weeks in the US, making it the most common type prevalent in the country.
“It is by far the most transmissible subvariant,” Van Kerkhove told reporters during a press conference in Geneva on Wednesday. “This is because of the mutations that are within this subtype of omicron that allow this virus to adhere to the cell and replicate more easily.”
Van Kerkhove said that so far it has been detected in 29 countries but it could be even more widespread. He added that tracking Covid variants has become difficult as genomic sequencing is declining across the world.
The WHO has no data yet on the severity of XBB.1.5, but at this time there is no indication that it makes people sicker than previous versions of Omicron, van Kerkhove said. He added that WHO’s advisory group on tracking Covid variants is conducting a risk assessment on XBB.1.5, which it will publish in the coming days.
“The more this virus circulates, the more opportunities it has to mutate,” van Kerkhove said. “We expect further waves of infection around the world, but do not want this to translate into further waves of death as our countermeasures continue to work.”
The scientists say that XBB.1.5 is just as good at dodging antibodies from vaccines and infections as its relatives XBB and XBB.1, which were the two most immune-evasive subvariants until now. But there is a mutation in XBB.1.5 it binds more strongly to cellsWhich gives it a growth advantage.
As XBB.1.5 rapidly spreads in the US, China grapples with a spike in cases and hospitalizations after abandoning its zero-COVID policy late last year in response to social unrest. US and global health officials have said Beijing is not sharing enough data on the surge with the international community.
WHO Director-General Tedros Adhanom Ghebreyesus told reporters in Geneva on Wednesday: “We continue to ask China for more rapid regular reliable data on hospitalizations and deaths, as well as more comprehensive real-time viral sequencing. “
A growing number of countries, including the US, are requiring airline passengers from China to test negative for COVID before boarding their flights. China’s foreign ministry has said such measures lack scientific basis and accused governments of manipulating COVID for political purposes. But the WHO director-general said the needs were understandable given the limited data coming from China.
“With the circulation so high and comprehensive data not being revealed in China, it is understandable that some countries are taking steps that they believe will protect their citizens,” Tedros said on Wednesday.
Beijing’s Centers for Disease Control and Prevention shared data with the WHO on Tuesday indicating the BA.5 sublineages, BA.5.2 and BF.7 account for about 98% of all infections in the country. But van Kerkhove said China is not sharing enough sequencing data with the vast country.
“It’s not just a matter of knowing which variants are at play,” Van Kerkhove said. “We need the global community to assess these, to look mutation by mutation to determine if any of these are new variants circulating in China but around the world.”