There are five or six variants that have a convergence of five or more mutations on the Spike and also have a significant growth advantage and enhanced immune evasion. Scientists call it “soup of variants”
It seems that the coronavirus is evolving in a different way from what it had accustomed us to: instead of selecting a unique strain destined to supplant the other (as it was for Omicron with Delta), there are more new variants (all derived from Omicron) which have the same mutations that arose independently of each other. It might seem that they are “competing” to emerge and become dominant, but this is not necessarily the case: we could also find ourselves living with what scientists have called a “Soup of variants”.
The “soup of variants”
The most notable group groups five or six variants that have a convergence of 5 or more mutations on the Spike and they also have a growth advantage significant and one increased immune evasion. The group takes the imaginative name of Pentagon when it incorporates 5 variants ed Exagon when it incorporates 6. In the Pentagon the main lineages included are: BQ.1.1, BN.1, XBB, BA.2.75.2 and others. In fact, World Health Organization (WHO) officials said they are monitoring themselves more than 300 points by Omicron. The fact that the same mutations arise independently suggests that those mutations confer an advantage. This “group” dynamic is called “convergent evolution».
“Cerberus” is the “strongest” one
If you were to “bet” on one sub-variant out of many, the bets would converge on BQ.1.1: a descendant of BA.5 which appears to have a considerable transmission advantage over BA.5 itself, similar to the advantage BA.5 itself had over BA.2 (and early laboratory studies also show its potential for immune evasion). The variant also had its own nomignolo social, Cerberusbut it is still rare: around 300 sequences, mostly confined to Europe, the United Kingdom and Nigeria.
In the graph above, compiled by Tom Wenseleers, professor of evolutionary biology, theoretical biology and biostatistics at the Catholic University of Leuven in Belgium, we see the (daily) growth advantage of some of the lineages mentioned over BA.5 (the variant in circulation), where BQ.1.1 grows just under 15% per day.
In Italy still BA.5
Cerberus has not arrived in Italy: according to the latest monitoring of the variants dated 29 September and provided by the Istituto Superiore di Sanità (ISS), the Omicron variant represents almost all of the sequences deposited. 7 sequences attributable to the BA.2.75 lineage (the one nicknamed Centaurus) and 6 to the BA.2.75.1 sub-lineage have been reported. In the last week of sampling, the percentage of BA.4 and BA.5 on the total of the deposited sequences was equal to 6.2% and 93.8%, respectively.
Rising cases
It is not known whether the infections are increasing in Europe (up 8%) and not in the rest of the world, are led by new groups of variants or, rather, by reinfections and people who get sick because the protective measures have been removed everywhere and people are more in closed environments without perhaps the fourth or third dose of vaccine. The highest number of new weekly cases was reported by Germany, but infections are also increasing in Italy: the reinfection rate approaches 20% e the weekly incidence it rises to 441 cases per 100 thousand inhabitants, compared to 325 last week. L’Rt medium calculated on symptomatic cases it is equal to 1.18, an increase compared to the previous week and higher than the threshold value. The intensive care employment rate it rises to 1.8% against 1.4% last week.
The forecasts of the experts
“We have known Sars-CoV-2 for almost 3 years – says the immunologist of the State University of Milan, Sergio Abrignani, to the time.news agency -: we have learned that
after a time ranging from 4 to 8 months it generates a new variant
. So it’s plausible to happen again. The people most at risk are those over seventy ”. The fourth dose for the frail is important at this stage: “A new pandemic wave is starting which unfortunately will find many elderly people who have not vaccinated themselves with the fourth dose and therefore in fact will not be protected against serious illness – observes Walter Ricciardi, professor of Hygiene at the Catholic University of Rome, guest on Radio 1 -. It would be appropriate for everyone to take the fourth dose – he adds – since less than 30% of those over 80 have done so. The impact (of the new wave of cases, ed) will not be the dramatic one of the past years, but there will certainly be a strong impact: it is a wave, not a tsunami “, concludes the expert.
October 8, 2022 (change October 8, 2022 | 15:53)
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