Since May of this year, experts and health authorities have been keeping a closer eye on a new corona variant. BA.2.75 was discovered in India and appeared to be spreading there. When the variant also appeared in a number of European countries and in the USA, concern grew that the next wave, following the currently dominant BA.5 variant, could be emerging here. So far, however, this concern has not materialized.
In its last weekly bulletin of July 11, the Indian Sars-CoV-2 consortium (INSACOG) mentions BA.2.75, but does not quantify its share of the circulating variants. The virus version is being observed in every state, but so far there has been no more severe disease progression and no increase in hospitalizations. BA.2 continued to dominate in first place and BA.2.38 in second place. Since then, INSACOG has not published any further figures, so the latest figures are missing. The Indian Ministry of Health also sees no locally skyrocketing case numbers, but rather a fairly scattered spread.
New category: “observed omicron subvariant”
The European health agency ECDC and the World Health Organization (WHO) are also following BA.2.75, but so far only as a “variant of interest” (VOI) and – in a newly created category – as an “observed omicron subvariant”. This means that the authorities see evidence of a change in the spread, for example due to a greater risk of infection, more severe courses or declining immunity in the population. What exactly piqued their interest has not been made public.
The BA.2.75 variant of the Sars-Cov-2 virus is a descendant of the earlier BA.2 version and has eight new mutations on the spike protein responsible for binding to target cells accumulated. The mutations affect previously unchanged spike regions. Some mutations seem to make the virus attach better to our cells. Other changes could cause that our antibodies don’t fit as well and eliminate the pathogen less effectively.
We have been confronted with the corona virus and the pandemic for almost two years now. The large complex of topics provides a lot of material for reporting. Here is a selection of articles about new variants, symptoms such as Long Covid and news about the vaccines.
These potentials and the geographic spread raised concerns with the molecular biologist Ulrich Elling from the Institute for Molecular Biotechnology in Vienna. Between BA.2 and the currently dominant BA.5 variant worldwide – at least on the spike protein – lie only three mutations, but BA.5 eludes the immune system much better.
The Robert Koch Institute (RKI) also stated in its current weekly report of July 28, albeit somewhat briefly: “The mutation profile of this variant indicates pronounced immune escape properties.” However, it is currently still unclear whether this means a growth advantage compared to the “BA.4 and BA.5-dominated events, as in Germany”. In this country, the RKI has only recorded four sequenced BA.2.75 cases, although the number of unreported cases is likely to be higher, as always. Since then, BA.2.75 has also been detected in some European countries in one to two-digit case numbers.
BA.2.75 share in Asia
The Australian data visualization specialist Mike Honey, who had searched for two BA.2.75-specific mutations in the international genome sequence database GISAID, tweeted more recent figures from Asia. Accordingly, the BA.2.75 accounted for 18 percent of sequenced samples in India at the end of June. Honey also determined using GISAID data at the end of July in Singapore a 5 percent growth advantage of BA.2.75 per day over all other BA.2 variants and one 10% growth advantage over BA.5 and BA.4 out.
It remains to be seen to what extent this will remain the case. Overall, it seems too early to make a definitive forecast as to whether and how much VA.2.75 will spread and whether it can displace BA.5. In India itself, according to unofficial figures from independent data analyst Vijay Anand, the Overall growth peak already passed in some provinces and the number of cases will decrease again in many places.
Several experts believe that concerns about the proliferation of the BA.2.75 variant, which one Twitter user gave the catchy name “Centaurus”, i.e. the wild centaur from Greek mythology, are unfounded. On the one hand the number of cases increased sharply only in a few provinces in which BA.2 had previously been dominant rather than BA.5said the US cardiologist Eric Topol from the Californian Scripps Research Translational Institute, who regularly curates new corona specialist publications on Twitter.
Bioinformatician Tulio de Oliveira from South Africa’s Stellenbosch University, who specializes in the spread of infectious diseases, was even clearer: “I disagree that BA.2.75 or Centaurus is of concern“. The number of cases and, above all, the deaths have increased only slightly in India. The prevalence, i.e. the frequency of disease, is also not increasing. Last but not least, there is no data to date that indicates a changed – worsened – pathogenicity. The scientist had with his Team first identified the beta and omicron variants.
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