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Considerable escape of SARS-CoV-2 Omicron to antibody neutralization


Planas D, Saunders N, Maes P, Guivel-Benhassine F, Planchais C, Buchrieser J, Bolland WH, Porrot F, Staropoli I, Lemoine F, Péré H, Veyer D, Puech J, Rodary J, Baele G, Dellicour S, Raymenants J, Gorissen S, Geenen C, Vanmechelen B, Wawina-Bokalanga T, Martí-Carreras J, Cuypers L, Sève A, Hocqueloux L, Prazuck T, Rey FA, Simon-Loriere E, Bruel T, Mouquet H, André E, Schwartz O.

The SARS-CoV-2 Omicron variant was first identified in November 2021 in Botswana

and South Africa1–3. It has since spread to many countries and is expected to rapidly

become dominant worldwide. The lineage is characterized by the presence of

around 32 mutations in spike—located mostly in the N-terminal domain and the

receptor-binding domain—that may enhance viral fitness and enable antibody

evasion. Here we isolated an infectious Omicron virus in Belgium from a traveller

returning from Egypt. We examined its sensitivity to nine monoclonal antibodies that

have been clinically approved or are in development4, and to antibodies present in 115

serum samples from COVID-19 vaccine recipients or individuals who have recovered

from COVID-19. Omicron was completely or partially resistant to neutralization by all

monoclonal antibodies tested. Sera from recipients of the Pfizer or AstraZeneca

vaccine, sampled five months after complete vaccination, barely inhibited Omicron.

Sera from COVID-19-convalescent patients collected 6 or 12 months after symptoms

displayed low or no neutralizing activity against Omicron. Administration of a booster

Pfizer dose as well as vaccination of previously infected individuals generated an

anti-Omicron neutralizing response, with titres 6-fold to 23-fold lower against

Omicron compared with those against Delta. Thus, Omicron escapes most

therapeutic monoclonal antibodies and, to a large extent, vaccine-elicited antibodies.

However, Omicron is neutralized by antibodies generated by a booster vaccine dose.

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