[HOT] : The Omicron variant escapes the serum of people vaccinated with Pfizer and AstraZeneca

Alpha, Beta, Delta, all the variants of the coronavirus that emerged after the development of anti-Covid vaccines more or less escape the neutralizing antibodies generated by the injection. Preliminary studies indicate that Omicron is no exception!

In a pre-published study on medRxiv, scientists at the University of Oxford put the serum of people vaccinated with Pfizer or Astra Zeneca against variants of SARS-CoV-2, including the latest Omicron. As was feared, the Omicron variant escapes neutralizing antibodies present in the serum of the vaccinated, much more than the other variants. This rather modest study, since it was carried out on only 43 sera and with variable results depending on the individual, should be reviewed by peers and then confirmed by other publications.

The Omicron variant seems to escape the power of vaccines. © famveldman, Adobe Stock

Neutralizing antibodies lacking in the face of the Omicron variant

The neutralization test was done for the Omicron variant, Delta, Beta and a variant close to the original source. Scientists used serum from participants in the Com-Cov study – 21 people doubly vaccinated with Pfizer and 22 with AstraZeneca. The sera were collected 28 days after the second dose.

Among the variants tested, Omicron is the most immune to the neutralizing power of antibodies, especially in people vaccinated with AstraZeneca. In them, the neutralizing antibodies effective against Omicron were so few that they could not be detected during the tests. For people vaccinated with Pfizer, the mean neutralizing antibody titer for the variant Delta is 558 against only 54 for the Omicron variant. This trend will need to be confirmed by further testing.

The hyper-mutated S protein of the Omicron variant distances it from other phylogenetically variants and from the strain used to design the vaccines. If the Omicron variant becomes the majority, the study authors believe that the vaccines will have to be adapted. They write: “If this were to happen, it might be necessary to produce vaccines suitable for Omicron. However, due to Omicron’s antigenic distance, they are unlikely to provide protection against previous strains. “

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