New coronavirus subtype : what is known about BA.2.75

A new corona subvariant was discovered in India in June. The data situation is still sparse, but BA.2.75 could also become relevant in Germany. What is known about the subvariant?

The omicron subvariant, designated BA.2.75, was first discovered in India. Now it has also been proven in Europe. And individual cases of BA.2.75 have also occurred in countries such as Canada, Australia, New Zealand and Great Britain.

What is known about the distribution of subvariant BA.2.75?

So far, in Germany according to the Robert Koch Institute (RKI) three cases of the BA.2.75 subvariant confirmed. However, relatively few PCR tests are sequenced in Germany. Therefore, scientists cannot yet say how quickly this subvariant will spread in Germany.

The exact data of the sequencing results from the RKI would also always have a delay of around four weeks, says the virologist Manuel Krone from the University Hospital Würzburg. The molecular biologist Ulrich Elling from the Austrian Academy is responsible for sequencing monitoring throughout Austria and has pointed out the possible danger of BA.2.75 in a Twitter post.

In an interview with the SWR Elling explains that only a few BA.2.75 cases have been detected worldwide. With the small number of cases, however, one has to consider how little sequencing there is in the countries. Therefore, there is hardly any data on the new corona subvariant. Elling is monitoring the situation in India very closely. BA.2.75 has already been detected in several regions there. So far there has been India 213 proven cases. However, the molecular biologist assumes that the number of unreported cases is high.

How dangerous is BA.2.75?

It is still too early to assess the threat posed by the new BA.2.75 Omicron variant. Richard Neher from the Biozentrum Basel emphasizes the sparse data. Other experts also point out that one can only speculate about the danger of the variant at the moment. So far, however, no more severe course of the disease than BA.2 and BA.5 is known.

If new forms are under strict observation, they are “variant of interest” (VOI, variant under observation). Virus variants of the prevailing mutations, which are either more easily transmitted or evade the immune system, are given the designation “variant of concern” (VOC). BA.2.75 has not yet been assigned to any of these groups by the RKI and the WHO. However, the omicron lineage is generally considered a “variant of concern”.

How is BA.2.75 different from other variants?

BA.2.75 already makes it clear in the name that it is a BA2 line and probably also originated from this virus type. the Omicron variants begin with the letters “BA.” and are counted up if they are considered as independent subvariants. So: BA.1, BA.2, BA.3, BA.4, BA.5. The variant BA.2.75 is not counted as an independent subvariant, but is the 75th subsubvariant of subvariant BA.2.

The BA2 variant has been extended by several mutations, explains Ulrich Elling. The omicron subvariant BA.5 differs from BA.2 with three mutations on the spike protein. This discrepancy alone was enough for the variant to quickly gain acceptance. BA.2.75 has eleven new mutations, eight of them in the spike protein. These changes could facilitate reinfections: “The eleven mutations in which BA.5 and BA.2.75 differ could enable another wave, since the immunity of BA.2 and BA.5 may not be protective,” speculates molecular biologist Ulrich Elling .

The virologist Krone like them Virologist Isabella Eckerle assume that common PCR tests can also reliably detect infections with the BA 2.75 subvariant.

Why is this variant so popular in India?

There are assumptions that the rapid spread in India is due to the fact that the BA.2.75 variant is also contagious for people who already have BA.2. Elling explains: “In the meantime, a country-specific immunity, so to speak, has developed in every country.” In South Africa, for example, there was a very strong BA.1 wave. In the South African context, the BA.5 variant managed to bypass BA.1’s immune protection. India, on the other hand, struggled with the BA.2 wave. Whether BA.2.75 circumvents the protection of BA.2 would also be relevant in Germany. In addition to a strong BA.1 wave, Germany also experienced a very strong BA.2 wave.

Which variant poses the greatest threat in Germany?

The experts are currently concerned above all about the BA.5 wave. It is currently responsible for most corona infections in this country and the experts assume that the number of unreported cases is very high. Many researchers expect that the Omikon BA.5 variant will remain the primary threat and will continue to spread.

Model calculations support the assumption that the summer wave will not be banished so easily. It is difficult to predict what role subvariant BA.2.75 will play and how much influence it could have. Because it does not have to be that one of the subvariants prevails, coexistence is also possible. Molecular biologist Elling thinks this scenario is conceivable: “It could also happen that both variants coexist, that is, exist side by side.”

What do the mutations mean for the adaptation of the vaccines?

“The frustrating thing is, our adaptation to the virus works much more slowly than the virus’ adaptation to our immunity,” emphasizes molecular biologist Elling. The fast mutations cannot be caught.

The vaccines adapted to Omicron, which are currently in the so-called rolling review-Procedures at the EMA, both from BioNTech and Moderna, have been primarily adapted to the BA.1 variant. However, BA.1 infection protects little against infection with BA.5. This means that “we can hardly protect ourselves from the subtype BA5 with the B1 vaccine,” explains Ulrich Elling.

When a new vaccine is rolled out, new variants are created, such as BA.2.75 now. The eleven mutations that occur here again present the vaccine with new challenges. According to Elling, it is not possible to prevent the waves directly, you can only try to keep the immunity, i.e. the protection against severe courses, stable.

The virologist Krone makes it clear that a distinction must be made between different goals when it comes to vaccinations. There is the vaccination goal: prevent disease, prevent hospitalization and death. The other goal is to stop the spread. The vaccine, which was originally adapted to the wild type of the coronavirus, has met all of these vaccination goals for the time being. In the Omicron line, vaccination is still able to provide good protection against death, severe courses and hospitalization, but only to a limited extent against infection, disease and further spread.

Are there alternatives to the classic vaccines?

Elling mentions that one sees an opportunity in alternative forms of vaccination. Intensive research is continuing on the combination of new vaccines and drugs. A nasal spray could also be a new approach here. This is a physical barrier to prevent infection.

Tübingen researchers are in the process of developing a special To develop a corona vaccine for the immunocompromised. With the currently approved vaccines, the immune system is only trained with parts of the spike protein, i.e. with the corona spikes. The Tübingen vaccine consists of a total of six proteins from the coronavirus and could therefore trigger a broader immune response in the body, which may also provide better protection against infection with new variants.

According to Krone, the vaccinations and infections have already built up good immunity in the population, which hopefully will not be intimidated by subvariant BA.2.75 and its mutated spike proteins.

Even if the data situation is still very sparse overall, there are indications that BA.2.75 definitely has the potential to become established.