Omicron 2 and (perhaps) Xe could “escape” the swabs, which retain the ability to identify positivity but are no longer enough to understand which variant one was affected by. All while, in the world, it sequences less
Omicron BA.2 has definitively supplanted Omicron BA.1 and is responsible for over 90% of Covid infections worldwide. It is the latest bulletin from the World Health Organization to describe the situation of the variants. In the last week of March, BA.2 is present in 93.6% of the samples deposited on Gisaid, the database of the genetic sequences of the virus; 4.8% are BA.1.1, while original Omicron (BA.1) counts just 0.9% of the samples.
According to the World Health Organization report, BA.2 surpassed BA.1 globally in the second half of February. Today it is dominant almost everywhereexcept in America where it is at 65.8%.
As for the characteristics of BA.2, according to the latest research, an infection with BA.1 confers close to 95% protection against BA.2 and, in cases of reinfection, the symptoms are mild.
For Xe (the recombinant variant resulting from a mix between Omicron BA.1 and BA.2), the first estimates suggest that it has a 10% advantage in terms of transmissibility over BA.2, but further confirmation is needed on this point.
The deletion of the S gene that is not in Omicron 2 (and perhaps not even in Xe)
At the moment, there are no losses of efficacy on Omicron 2 compared to Omicron 1 of treatments or diagnostic tests, both molecular and rapid: in essence, the swabs are able to understand that one is positive for the coronavirus.
The problem, however, is that Omicron’s “sister” is difficult to identify, since it does not have the “deletion of the S gene»Omicron BA.1 feature. In other words: you understand that you are positive, but not by which variant you were affected.
To understand this, it is necessary to sequence the samples and this implies a laboratory capacity that not all countries have. The lack of the S gene allowed instead of suspect that a sample belongs to the Omicron variant of the “classic” type directly from the swab (without sequencing, which is done later).
We do not yet know if Xe is missing the S gene. “Xe will be considered part of the large family of the Omicron variant until such time as they are reported. significant differences in transmission and disease characteristicsincluding gravity, ”says the World Health Organization.
The presence of Xe was reported in Britain in January, with over 600 sequences.
Why is sequencing important?
Why is the fact that a variant being identified – that is, recognized as such – so important?
The World Health Organization warns that “the rate of evolution of the virus and the risk of new variants emerging, including recombinant ones, are still very high”.
For this reason it raises some concern the decrease of the sequences deposited on Gisaid: they were more than 284 thousand in the first week of the year, to drop to 65 thousand in the last weeks of February.
“Although the decrease in sequences is consistent with the general trend of new cases observed globally, it may also reflect changes in epidemiological surveillance policies in some countries,” the report reads. In Italy a new rapid survey of the Higher Institute of Health will examine the samples collected on 4 April by genomic sequencing to estimate the prevalence of circulating variants.
Occupation of ordinary departments at 16%
In our country, the curve of new Covid cases remains in a stable situation, but always on high numbers and this has a direct consequence: the number of patients requiring hospital assistance is increasing. To prove it is the figure on the employment of ordinary departments rose to 16%, thus exceeding the alert threshold set at 15%. An alarm bell, while in Italy the victims have exceeded 160 thousand since the beginning of the pandemic. A picture that is accompanied by a growing concern also at European level for the persistence of “significant” outbreaks in various countries. According to data from the National Agency for Regional Health Services (Agenas), the occupancy of beds in non-critical area hospital wards by Covid patients has reached 16% and exceeded 20% in 7 Regions. Intensive care employment is stable at 5% nationwide, below the 10% alert threshold, but remains at 10% in Calabria and 12% in Sardinia.
April 7, 2022 (change April 7, 2022 | 14:06)
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