A team of researchers fromUNIGE andHUG demonstrated, after comparing the neutralization capacity induced by the different variants of SARS-CoV-2the extraordinary attitude of the variant Omicron in dodging our immune system.
The results of the Research have been published in the scientific journal Nature Communications.
Because Omicron evades all the antibodies of the other variants
The current wave of COVID-19 showed a particularly high risk of reinfection by the SARS-CoV-2 keiant Omicron. Center for Emerging Viral Diseases of the University of Geneva (UNIGE) andGeneva University Hospital (HUG) carefully studied the antibody neutralizing ability of 120 people infected with the original SARS-CoV-2 strain, or one of its alpha, beta, gamma, delta, zeta, or omicron variants (sub-variant BA.1).
Unlike its predecessors, omicron appears to be able to evade antibodies generated by all other variants. In vaccinated individuals, although the neutralization capacity is also reduced, it remains far superior to natural immunity alone. This could explain why the variant in question is responsible for a sharp increase in vaccine infections, but not hospitalizations.
Since the start of the pandemic, the HUG outpatient testing center has offered Covid19 testing to the community: “As the national referral center for emerging viral diseases, we have the ability to sequence a large proportion of positive cases to monitor for the emergence of new variants“, he has declared Isabella EckerleProfessor at the Department of Medicine of the UNIGE Faculty of Medicine and Dean of HUG-UNIGE Center for emerging viral diseases, which led this work.
“Since the beginning of 2020 we have collected samples of the original virus and all its variants that appeared in Switzerland, even the rarest ones such as gamma or zeta. This makes it a comprehensive collection of specimens from individuals with different infection backgrounds, collected according to an identical protocol“, Professor Eckerle continued.
The team of researchers took blood samples from 120 volunteers previously infected with one of several variants, unvaccinated or vaccinated and infected, before or after vaccination: “With a mean age of 28 to 52 years, with no major comorbidities and a mild to moderate form of COVID-19, this cohort accounts for the majority of cases in the community“Explained Professor Isabella Eckerle.
The aim of this study was to determine how well the antibodies generated during the first infection were able to neutralize the different variants of SARS-CoV-2: “Omicron has been shown to be the most effective in evading pre-existing natural immunity, as well as, to a lesser extent, vaccination-induced immunity.“, he has declared Benjamin Meyerresearcher at the Center for Vaccinology at the Department of Pathology and Immunology of the UNIGE Faculty of Medicine.
In fact, the levels of antibodies against ancestral SARS-CoV-2 in individuals given the vaccine are about 10 times higher than in people who have only developed post-infection immunity. Furthermore, the combination of the two, known as hybrid immunity, appears to maintain even higher and wider levels of reactive antibodies.
“Thus, omicron can evade existing immunity and cause an infection, but hospitalization and death due to COVID-19, even with Omicron, are still reduced after vaccination.“. However, SARS-CoV-2 retains an astonishing ability to mutate, which also appears to accelerate: “Vigilance is still needed, especially as epidemiological curves have increased dramatically since the emergence of BA.5, the most recent sub-variant of omicron“, Professor Isabella Eckerle specified.
The research team also developed the antigenic mapping of the different variants, based on the same model used to determine the antigenic changes of influenza: “This computational method allows to represent the distance between the characteristics of the antigens of the variants involved: the further they are, the less effective the antibodies generated during previous infections will be. It turns out that the omicron serotype is totally different from the others, as is the zeta variant, which quickly disappeared“, He reported Meriem Beklizpostdoctoral researcher in Isabella Eckerle’s laboratory and first author of this study.
For the first time, a respiratory virus has been studied so closely: “This virus, which belongs to the same family of coronaviruses that cause nearly a third of common colds, can, in the absence of measures, spread like wildfire in populations lacking immunity to fight it.“Explained Benjamin Meyer. “We now have molecular sequencing and observation tools that were unknown a few years ago, the discoveries we are making today open up perspectives and understanding that will be useful far beyond SARS-CoV-2 ″.
The COVID-19 pandemic has also enabled unprecedented acceleration in vaccine research. Several teams are now working on nasal spray vaccines, which are easier to administer and, more importantly, can act directly in the mucous membranes of the nose and throat, where they are most useful.
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