Covid: First data points to Omicron re-infection risk


The first real world data showing the coronavirus variant Omicron may evade some of our immunity has been reported by scientists in South Africa.

Scientists have noticed an increase in people contracting Covid several times.

It is a quick and not definitive analysis, but it fits with the concerns about mutations that the variant possesses.

It is also unclear what this means for vaccine protection.

A week after the variant was called Omicron, the world still strives to understand the real threat posed by the variant. But now, the first pieces of a large and complex puzzle are assembled.

We already know that the variant has mutated a lot, and South African officials have warned that this is causing an increase in cases there.

The last puzzle piece is understanding how likely it is that someone who has already had Covid will catch Omicron.

It has also been detected in more than 30 countries.

Scientists have analyzed nearly 36,000 suspected re-infections in South Africa to look for changes in re-infection rates (twice or more) during the pandemic.

They showed that the risk of re-infection did not increase during the beta or delta wave. There is despite laboratory studies suggesting that these variants may bypass some immunity.

However, they are now seeing an increase in re-infections. They haven’t tested all patients to prove they are Omicron, but time suggests that the variant is the driving force.

The study, which other scientists have not formally reviewed, estimates that omicron could cause reinfection twice as much as previous variants.

Professor Juliet Pulliam of the University of Stellenbosch and one of the researchers said, “These findings suggest that Omicron’s selection advantage is due, at least in part, to an increased ability to infect previously infected people,”

But it is still just one piece of the puzzle.

There are questions about how much is a factor in lowering immunity and how much each variant could take off now.

In addition, this was a quick analysis, and more data will arrive over time. The high burden of HIV suppressing the immune system in the country also makes it difficult to interpret the results for the rest of the world.

Laboratory studies showing how well antibodies can attack the virus are expected to work next week.

Does the timing matter?

In South Africa, only 24% of people are fully vaccinated. The researchers said their findings could have “major implications” in similar countries with high natural immunity to infections.

However, Professor Pulliam stressed that “they cannot assess whether Omicron is also escaping vaccine-derived immunity” because they did not have this data.

This makes it harder to understand what would happen in countries like the UK that vaccinated many more people and quickly introduced booster doses to enhance immunity further.

Strengthening the immune system should compensate for some variant tricks for immune system evasion.

Professor Paul Hunter of the University of East Anglia said: “This article implies that Omicron will be able to overcome natural and likely vaccine-induced immunity significantly.

“But the conclusion is not yet clear, although it is doubtful that this is a complete escape.”

The gut instinct of most scientists is that even if vaccines are less effective in preventing Covid from spreading, their primary mission of preventing serious illness and death will be better.

However, Omicron could still cause a problem, even if it does. If the variant is capable of causing a sudden large wave of new infections, it could put pressure on hospitals again.

It’s too early to know for sure, as it takes a few weeks before the virus needs to be treated in the hospital. South Africa is also a relatively young country, meaning that Covid seems milder than if it spread to a larger population.

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Professor Francois Balloux of University College London said: “The increased estimated reinfection capacity of the omicron variant to cause re-infection is not too surprising and could be expected largely due to the large number of mutations in the spike protein carried by the omicron variant, which increases capacity of the omicron variant to avoid host immunity”.

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