Covid-19: New study shows why Omicron is highly transmissible

A new study suggests that Omicron mutations increase the infectivity of SARS-CoV-2 virus-like particles and decrease antibody neutralisation.

This study was in the journal 'Proceedings of the National Academy of Sciences' (PNAS) on July 19. It compares four variants of SARS-CoV-2 shows how the Omicron variant is more adept at entering cells and escaping neutralization from existing vaccines or prior infection, potentially contributing to the variant's high transmissibility.

Researchers examine the virus using virus-like particles (VLPs) that imitate the SARS-CoV-2 proteins' structural characteristics.

Antibodies and vaccinations

In contrast to the original B.1 strain, antibodies from the same individual who had received two vaccinations were up to 15 times less effective at neutralising Omicron. Nevertheless, the neutralising activity against Omicron was significantly increased from participants who had received a third mRNA vaccine within 16 to 21 days.

According to the findings, the authors hypothesise that Omicron may be particularly contagious in part because it is a harder strain to neutralise.

Notably, compared to ancestral variants, including Delta, Omicron is less likely to be neutralised, although antibodies in those who have gotten mRNA vaccines show better results than those with antibodies from other vaccines or previous infections. Booster shots raise Omicron's neutralisation titers, but they are still significantly lower than for earlier types. These results support the use of mRNA vaccination boosters to improve antibody-based protection against Omicron infections.

(The researchers' approach to analysing the impact of mutations in structural proteins has a few limitations which may not work for all variants and sub-variants.)

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