Sars cov 2 is not yet a seasonal disease

"SARS-CoV-2 is not yet a seasonal disease "Many see the milder omicron variant of the coronavirus as a chance to end the pandemic. Which role of the omicron subtype BA.2 plays a role in this, explains oAW molecular biologist Ulrich Elling in an interview.

Influenza infections are seasonal illnesses that occur less frequently in the warm months. SARS cov 2 has not yet developed in this direction, however. © Unsplash/ Yoav Aziz

There's also some good news: Immunity in the population is moving in a clear direction, more people are building up immune protection against SARS-CoV-2, and Omikron has reduced disease severity. But we have not yet reached an endemic state, says Ulrich Elling of IMBA – Institute of Molecular Biotechnology of the Austrian Academy of Sciences (oAW): "The infection process is still very much driven by the variant in question."

In the interview, the molecular biologist explains what is involved in the omicron subtype BA.2 and the recombination of delta and omicron, "delta cron".

Omicron variant BA.2 is more infectious

Currently, there is a lot of talk about Omikron being the end of the pandemic. How do you see this?

Ulrich Elling: A great many people have already become infected and many are still becoming infected, especially those who have not yet been vaccinated. Due to regular infections or vaccinations, we slowly build up an immune protection. On the other hand, it must be remembered: which variants of the virus might evolve in the future is uncertain, and infection with omicron protects z.B. Not before infection with delta.

What variants of the virus might develop in the future is uncertain.

Speaking of new variants. Since the end of February, the omicron subtype BA has dominated.2 the infection incidence in Austria. What does it mean? BA.2 is more infectious than BA.1. Has therefore become established. 2 is more infectious than BA.1. Has become more prevalent because of this.1 and that's why it has caught on. There is evidence that BA.2 has shorter serial intervals: The contagion time from one patient to the next has decreased significantly. These are chains of infection as in time lapse. To what extent BA.2 bypasses immune protection more strongly than BA.1 cannot be said precisely because of conflicting data from Denmark and England. In the data I examined from Austria, greater evasion of immune protection has not been confirmed so far. While laboratory data suggest that the disease progression in BA.2 somewhat more severe than BA.1, this cannot be observed in hospitals.

BA.2 will play a role among the elderly.

Brings BA.2 a new wave?

Elling: BA.2 takes over, displaces and thus keeps the infections still high. While the wave in BA.1 started with the young, it is now slowly reaching the older generations. BA.2 will therefore play a role in the elderly. Something similar has been seen in England.

Little knowledge about delta crones so far

What's the deal with the mixed variant "deltacron" that has recently surfaced in the UK?

Elling: At present, we only know that a recombination of Delta and Omikron has occurred, i.e. a mixing of the viral genomes. Whether this mixed variant has the infectivity of Omikron – or even a higher one – is still unclear. Also how the severity of the courses will be, we do not know yet. However, it shows that recombination between coronaviruses does occur. This has great relevance for the future.

A kind of cat-and-mouse game has begun: The virus is trying to escape our immunity and assert itself with new variants.

To what extent?

Elling: Since we have a high immunity worldwide, a kind of cat-and-mouse game has started: The virus is trying to escape our immunity and assert itself with new variants. However, this evolution does not follow a stepwise improvement like the famous Darwin's finches, but rather resembles a Black Swan evolution. Black swans", the term originates from economics, refers to unpredictable events that have a huge effect. Omicron is such a case.

So from a virological point of view, it is not possible to define what possible new variants will look like?

Elling: The mutations accumulate in a singular event, in a kind of black box, which we do not know exactly how and where it takes place. And that's why we can't say what selection criteria are important for it. So far, it has been observed that the virus variants became more infectious and worse in the course of the disease. With Omikron, these two sides of the virus decoupled for the first time: it became significantly more infectious, but milder in course.

Vaccination and medications important

Similar to influenza vaccination, will we have to adjust our vaccines each year to match the particular virus variant?

Elling: Sars-CoV-2 is not yet a seasonal disease that only occurs in winter. Delta has been observed to grow exponentially starting in early July. And Omikron emerged in the middle of summer in South Africa. So the infection event is still very much driven by the particular variant.

Sars-CoV-2 is not yet a seasonal disease that only occurs in winter.

In terms of immunity, we will have to try to match it as well as possible. T-cell immunity, i.e., protection against severe courses, has so far been provided by vaccines against all variants. But whether we have a realistic chance to adapt our vaccines preventively with a new variant remains to be seen. This was not successful with Omikron. Another important pillar will be drugs; the first really effective drug, Paxlovid, is now also available in Austria.


Ulrich Elling is a molecular biologist and research group leader at the IMBA – Institute of Molecular Biotechnology of the Austrian Academy of Sciences (oAW). He received his doctorate from the University of Regensburg. Received his PhD from the European Molecular Biology Laboratory (EMBL) in Heidelberg, Germany.

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