February 24, 2024

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How do COVID-19 Omicron variants evade the immune system?

How do COVID-19 Omicron variants evade the immune system?


Nature Communication: How do COVID-19 Omicron variants evade the immune system?


The recent surge in COVID-19 patients underscores the particularly high risk of reinfection with the Omicron variant of the novel coronavirus. Why is this so?

The research team from the Centre for Emerging Viral Diseases of the University of Geneva and the University Hospital of Geneva analysed the antibody neutralisation capacity of 120 patients infected with the original or mutant strains.


How do COVID-19 Omicron variants evade the immune system?



Unlike its predecessors, the Omicron variant appears to be able to evade the antibodies produced by all other variants.

For vaccinated individuals, although neutralization capacity also declined, it still far outperformed natural immunity.

This may explain why Omicron led to an increase in breakthrough infections rather than hospitalizations.

The results were published in the journal Nature Communications.


Isabella Eckerle, professor at the Faculty of Medicine at the University of Geneva, who led the work, explained:

“As the national reference centre for emerging viral diseases, we have the ability to sequence a large proportion of positive cases to monitor the emergence of new variants. Since the beginning of 2020 , we took samples of the original virus as well as all variants that have emerged in Switzerland, including the rarest variants such as Gamma or Zeta.”


The researchers collected blood samples from 120 volunteers who had previously been infected with different variants of SARS-CoV-2, either while unvaccinated or with breakthrough infection after vaccination.

“This cohort, with an average age of 28 to 52 years without major complications, had mild to moderate COVID-19 and represented the majority of cases in the community,” Eckerle explained.




Antibody levels increased tenfold after vaccination

The purpose of this study was to determine the extent to which antibodies produced during the first infection were able to neutralize different variants of SARS-CoV-2.

Co-corresponding author Benjamin Meyer of the University of Geneva explained: “The study shows that Omicron effectively evades pre-existing natural immunity, as well as immunity induced by vaccination.”

In fact, the level of antibodies produced in the vaccinated population About 10 times the level of antibodies produced after infection.


“As a result, Omicron can evade existing immunity and cause infection, but hospitalizations and deaths following vaccination have also declined.” Nonetheless, SARS-CoV-2 retains a surprising ability to mutate, and It seems to be accelerating. Eckerle added: “At this point, vigilance is still needed, especially since the epidemiological curve has been rising sharply after the emergence of the omicron subvariant BA.5.”


The scientists also used the model to map the antigens of the different variants.

First author Meriem Bekliz explained:

“This computational method can express the distance between the antigenic features of correlated variants: the further apart they are, the less effective the production of antibodies during a previous infection. It turns out that the Omicron serotype It’s totally different from other serotypes, so is the Zeta variant.”


Never before has a respiratory virus been studied so thoroughly. “This virus is a member of the coronavirus family, nearly one-third of the common cold is associated with coronavirus, and if nothing is done, it can spread like wildfire in people without immunity,” Meyer explained.


The COVID-19 pandemic has also accelerated vaccine research at an unprecedented pace.

Several teams are currently working on a nasal spray vaccine, which is easier to administer and, most importantly, works directly on the mucous membranes of the nose and throat, where they are most likely to work.



Neutralization capacity of antibodies elicited through homologous or heterologous infection or vaccination against SARS-CoV-2 VOCs

How do COVID-19 Omicron variants evade the immune system?

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