There are actually three new variants that have been featured. According to a report recently released by the UK Health Service, the two named XD and XF are combinations of Delta and BA.1 strains, or so-called “Deltacron” strains, which have been discussed for months, but were not significant. invasions in any country. XD is present in many European countries, but has not been detected in the United Kingdom, according to the report. XF caused a small cluster in the UK, but has not been detected there since 15 February. The variant that causes the most concern, it seems, is the one called XE. Like the other two new arrivals, the XE is a recombinant strain, meaning it consists of two previously distinct variants. But it is not a mixture of Deltacron. The XE actually consists of the original Omicron (BA.1) and the newer Omicron (BA.2) which has taken over the US. The World Health Organization released a report yesterday with some preliminary findings. “Recombinant XE was first identified in the United Kingdom on 19 January and since then> 600 sequences have been reported and confirmed,” the WHO document said. “Early estimates show a community growth rate advantage of ~ 10% compared to BA.2, however this finding requires further confirmation.” Further confirmation is becoming increasingly difficult, according to the WHO, which expressed concern this week about what it calls “the recent significant drop in SARS-CoV-2 testing by many Member States.” The data is gradually becoming less representative, less relevant and less powerful. “This undermines our collective ability to monitor where the virus is located, how it is spreading and how it is evolving: information and analysis that remains critical to effectively ending the acute phase of the pandemic.” Last week’s update from the UK Health Services Agency reinforces some of the allegations in the WHO report and urges you to be careful about jumping to conclusions. One difference between the two documents is that the WHO data and analysis appear to be more recent. From the HSA update in the United Kingdom: XE shows indications of Community transmission within the UK, although it is currently less than> 1% of total sequencing cases. Early growth rates for XE did not differ significantly from BA.2, but using the latest data as of March 16, 2022, XE has a growth rate of 9.8% above that of BA.2. As this estimate did not remain consistent as new data were added, it can not yet be interpreted as an estimate of growth advantage for the recombinant. The numbers were too small to analyze the recombinant XE by region. To be clear, XE represents only a small fraction of the cases worldwide. This may change, as XE is believed to be approximately 10% more contagious than the already more contagious BA.2. That means it could be about 43% more contagious than the original Omicron that hit the globe last winter. However, a new wave of infections from the now dominant BA.2 has not materialized, although restrictions have eased. So let’s hope that the trend with XE, if it exceeds BA.2, will be similar. Only time – and good supervision – will show.
