Activity of convalescent and vaccine serum against a B.1.1.529 variant SARS-CoV-2 isolate

Abstract

The B.1.1.529 (Omicron) variant of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) was identified in November of 2021 in South Africa and Botswana as well as in a sample of a traveler from South Africa in Hong Kong.1,2 Since then, B.1.1.529 has been detected in many countries globally. This variant seems to be more infectious than B.1.617.2 (Delta), has already caused super spreader events3 and has outcompeted Delta within weeks in several countries and metropolitan areas. B.1.1.529 hosts an unprecedented number of mutations in its spike gene and early reports have provided evidence for extensive immune escape and reduced vaccine effectiveness.2,4-6 Here, we investigated the neutralizing and binding activity of sera from convalescent, mRNA double vaccinated, mRNA boosted as well as convalescent double vaccinated and convalescent boosted individuals against wild type, B.1.351 and B.1.1.529 SARS-CoV-2 isolates. Neutralizing activity of sera from convalescent and double vaccinated participants was undetectable to very low against B.1.1.529 while neutralizing activity of sera from individuals who had been exposed to spike three or four times was maintained, albeit at strongly reduced levels. Binding to the B.1.1.529 receptor binding domain (RBD) and N-terminal domain (NTD) was reduced in convalescent not vaccinated but was mostly retained in vaccinated individuals.

The immunogenicity and reactogenicity of four COVID-19 booster vaccinations against SARS-CoV-2 variants of concerns (Delta, Beta, and Omicron) following CoronaVac or ChAdOx1 nCoV-19 primary series

“…The SARS-CoV-2 Omicron variant, recently identified in November 2021 has been reported to evade immunity induced from past infection or two vaccine doses [26-28]. Our results suggest that a third dose of BNT162b2 can overcome this immune evasion through the induction of neutralising antibodies.…”

Durability and cross-reactivity of SARS-CoV-2 mRNA vaccine in adolescent children

“…Encouragingly, the immune responses that have been generated display sufficient cross-coverage of the VOC, Omicron, with comparable immune responses to those reported in adults 8 . This could suggest that children develop a similar adaptive humoral immune response as seen in adults 9 , which may provide benefits to children as additional variants of concern emerge.…”

Interpretable and Predictive Deep Modeling of the SARS-CoV-2 Spike Protein Sequence

“…These results are broadly consistent with both a) predictions that the Omicron spike protein structure can evade antibodies and b) experiments measuring significantly lower neutralization by vaccinated and convalescent sera as compared to previous variants—including Beta, which, as Table 1 indicates, is significantly immune evasive itself. [166]–[171] This demonstrates the ability of the neural network model to generalize, as it predicts a reduction in neutralizing antibody titers of Omicron much greater than any other previously characterized variant considered individually. By contrast, when tested XGBoost an alternative methodology, it consistently overfit to the training data and predicted no more than a 2 or 3-fold reduction for any combination of maximum tree depth, regularization, and other hyperparameters.…”