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The new main role in the pandemic is currently played by Omikron. Virologists explain what else to expect.
How long will this go on with the pandemic? The answer to this depends heavily on how much versatility the coronavirus can still be expected to have. After 18 months of pandemic, virus researcher Emma Hodcroft from the University of Bern replies: Difficult to say. From an evolutionary point of view, 18 months are pretty short.
“Sars-CoV-2 has only just arrived in its new host, humans,” says Hodcroft. It is not yet known whether the virus has already found the “best version of itself”. The version that infects human cells perfectly, is perfectly passed on to the next human and can bypass the human immune system.
Omikron – a big leap
This is followed by the question of what relevant variants the virus has produced so far. «Within the variants that we have had so far, there has been a more gradual evolution. Then there were always small jumps. Those were the old variants that were classified as worrying: Alpha, Beta, Gamma, Delta, ”says Richard Neher from the University of Basel.
Alpha to Delta, four worrying, i.e. relevant variants. That was the status until a month ago. All four had rather small changes compared to the original version. Alpha and Delta were mainly more contagious, Beta and Gamma were somewhat immunevasive, which means that they were able to bypass the acquired immunity to a certain extent after infection or vaccination.
On these short time scales, the severity of the disease depends much more on the host and its immunological history than on the variants of the virus.
“Now we didn’t just have a little jump, but a huge leap,” explains Neher. He means the variant Omikron, which carries several dozen mutations. She is very different from everyone before. With consequences: Up until a month ago, one could hope that the coronavirus might not bring about a really good immune evasion – that is, the ability to undermine existing immunity.
Beta and gamma had a slight immune evasion, but little did the virus benefit in the first half of 2021. Delta, the variant that was far more contagious than any other, prevailed and became dominant worldwide.
Legend:
The new main role in the pandemic is currently played by Omikron, which is shuffling the cards again – and destroying the slight optimism that Delta and thus perhaps the pandemic are almost under control.
Keystone
In today’s highly immune world, gamma and beta might have had a chance. «We only now have a more or less comprehensive immunity. In some regions by vaccination, in others by primary infections. This changes the selection landscape, ”says Neher.
That means: Only now does the virus bring real advantages if it can infect people who have already been infected or vaccinated again, because only now there are really many of them. And Omikron shows: Corona controls the immune escape – quite well in fact.
They adapt year after year. The human immune system learns. Again the viruses adapt. And all over again. It’s like a dance, an equilibrium that continues to oscillate anew.
Influenza viruses and cold coronaviruses have been circulating in humans for decades, for centuries. Emma Hodcroft says, “Year after year they adapt. The human immune system learns. Again the viruses adapt. And all over again. It’s like a dance, an equilibrium that oscillates over and over again. ”
The newcomer Sars-CoV-2 initially seemed to only master a few dance steps. Omikron shows that you have to trust the newcomer more. At the same time, people’s immunity increases. That’s not so unimportant for the moment, says Neher: “On these short time scales, the severity of the disease depends much more on the host and its immunological history than on the variants of the virus.”
The virus will stay. After Omikron there will be new variants. Whether or not they make many people seriously ill depends not least on the dance mentioned.