CDC announced this week that the BA.2 omicron The variant, which is reportedly 30% more permeable than the original BA.1 Omicron strain – has dominated Among the new cases indexed United States, This is a shocking increase for the variant priced below this. 1% of all sequences As recently as Jan. But, as Americans are hearing about BA.2, a new, even more permeable version is already on the rise.
There are actually three new variants that have been given designations. According to a recently released report good From the UK Health Services Agency, the two called XD and XF are a combination of Delta and BA.1, or so called “deltacron“Strains, which have been talked about for months But did not make any significant inroads in any country.
Reportedly, XD is present in several European countries, but has not been detected in the UK. XF caused a small cluster in the UK, but has not been detected since 15 February. The version of greater concern, it seems, has been dubbed XE.
Like the other two new arrivals, XE is a recombinant strain, meaning it is composed of two pre-specific forms. But this is not a DeltaCron mix. The XE is actually made up of the original Omicron (BA.1) and the newer Omicron (BA.2), which have taken over the US
World Health Organization released a report With some preliminary findings tomorrow.
“The XE recombinant was first detected in the United Kingdom on 19 January and >600 sequences have been reported and confirmed,” reads WHO document. “Early day estimates indicate a community growth rate advantage of ~10% compared to BA.2, although this finding requires further confirmation.”
Further confirmation is getting harder day by day, according to who, which this week raised concerns about what it calls a “significant reduction in recent SARS-CoV-2 testing by several member states”. The data is becoming increasingly less representative, less timely and less robust. It inhibits our collective ability to track where the virus is, how it is spreading and evolving: the information and analysis that are critical to effectively ending the acute phase of the pandemic. ,
last week talks The UK health services agency confirmed some of the WHO reports and urged caution about jumping to conclusions. One difference between the two documents is that the WHO figures and analysis appear to be recent.
From the UK HSA Briefing:
XE shows evidence of community transmission within England, although it currently accounts for less than 1% of total sequenced cases. The initial growth rate for XE was not significantly different from that of BA.2, but using the most recent data as of March 16, 2022, XE has a BA.2 growth rate of over 9.8%. Since this estimate has not been consistent as new data are added, it cannot yet be interpreted as an estimate of the growth advantage for recombinases. The numbers were too small for the XE recombinant to be analyzed by region.
To be clear, XE only accounts for a small fraction of cases worldwide. This may change, given that XE is known to be about 10% more permeable than the previously more-permeable BA.2. This means it can be about 43% more permeable than the original omicron damage Globe last winter.
But a new wave of infections from the now effective BA.2 has not materialized, even as restrictions have been eased. So hopefully the trend with XE, should it compete with BA.2, will be the same. Only time – and good monitoring – will tell.