Not much is known about the new variety, as geneticist Ulrich Elling explained. However, the mutability of the SARS-CoV-2 pathogen shows that only an immune response that is as broad as possible will pave the way to the longed-for endemic.
Also proven in Austria
In Austria, too, BA.2 has already been detected through the systematic analysis of samples from sewage treatment plants, as Heribert Insam, head of “School Site Monitoring”, recently explained. In Denmark, which is well informed about the distribution of variants in the country, cases with BA.1 are declining again, but infections with Omicron BA.2 are increasing. A similar trend is indicated in England, according to Elling, who works at the Institute for Molecular Biotechnology (IMBA) of the Academy of Sciences (ÖAW).
18 mutations
The spike protein of the two subtypes differs significantly – specifically in 18 mutations. For comparison: the delta variant has a total of only eight mutations in the spike protein compared to the original virus. It is conceivable that BA.2 can escape an established immune protection even better. This could mean that people whose immunity was still able to fight off an infection with BA.1 may be less immune to a BA.2 infection. This is plausible, since BA.2 has a relatively large number of mutations in the receptor-binding domain – that part of the spike protein with which the pathogen docks to the cells and which many antibodies target – according to Elling.
Is BA.2 even more infectious?
Another possible explanation is that BA.2 could be even more infectious and multiply faster. This is conceivable, since it has completely new, but overall fewer mutations in the “completely different” N-terminal (NTD) compared to BA.1. The NTD are the three peaks of the S protein viewed from above. These structures are responsible for the fusing of virus and human cell. The many changes in BA.1 there could represent a disadvantage in propagation for this offspring, with which BA.2 may have less to contend with. This is probably the key to the fact that the previous BA.1 variant from Omikron is more difficult to penetrate deeper into the lungs and that the courses are milder.
“Omicron is milder on average”
In principle, a large number of people are already protected at least from severe courses with all SARS-CoV-2 variants including omicron through vaccination or past illness. Ellling: “Omicron is milder on average because it mostly infects protected people.” The scientist expects that this will probably not be much different with BA.2. However, it is unclear whether the subtype itself “is not another step in the wrong direction for the unvaccinated. We don’t know yet”.
Cut-throat competition has evidently also begun within the Omicron variant. It can be assumed that BA.2 will take the lead. Therefore, one should take a close look at what constitutes his advantage, emphasized Elling. The first data on this could be available in the coming week.
If the new sub-variant now prevails in Denmark or Great Britain, the omicron wave could become a kind of “double whammy”. However, the researcher estimates that those who have contracted the first variant are less likely to become infected with BA.2.
Development “still unpredictable”
Where the development of the corona virus will go overall is “still unpredictable”. The new variants always came from different directions. In order for SARS-CoV-2 to ultimately become endemic – i.e. to become a seasonally recurring pathogen that does not cause a major epidemic – an immune system is needed above all, whose T cells recognize the pathogen in as many different forms as possible. The T cells are a group of white blood cells whose job it is to recognize new threats and drive the acquired immune response. They can react more flexibly to a virus than antibodies, which are usually designed to be more specific.
According to Elling, the pandemic cannot yet be declared over for people who have already had an omicron infection: “We simply do not yet know which variants will come.” With every confrontation through vaccination or infection, however, the immune system builds up a broader response and the likelihood of progressively milder courses increases. The geneticist is therefore hoping for complex vaccines that, like influenza vaccines, contain many varieties of the virus. The fact that the T-cell immunity probably works quite well across all variants gives hope.
Source: Nachrichten
