Comparative efficacy of Original and bivalent mRNA vaccine using non-human primate model; contribute to the vaccine strategy against the next variant

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Presentation Time: 11:30 AM - 12:45 PM
Poster Board Number: B923
Abstract ID: 4766

Presenting Author:
Emiko Urano , Senior Researcher at Natl. Insts. of Biomed. Innovation, Hlth. and Nutrition

Abstract:

Although rapid vaccination has been progressing in the world, SARS-CoV-2 is going around the world due to the continuous emergence of several variants, and we still have prolonged Omicron waves. Therefore, we always come across the query of how effective the current vaccine is in the next emerging variant. We have established the evaluation system using the COVID-19 cynomolgus macaque (CM) model.

In the present study, CMs were immunized twice at 3 weeks intervals with either the original Comirnaty mRNA vaccine or bivalent Comirnaty Omicron BA.4/BA.5, then, immunized CMs were challenged at 4 weeks after the second shot of vaccination with either Wuhan or Omicron BA.5.

Antibodies against Wuhan were strongly induced by both the original and bivalent mRNA vaccine group, but against BA.5 were weakly induced only in the bivalent mRNA group. CMs challenged with the Wuhan virus were well controlled; however, original mRNA CMs could not protect against BA.5 infection.  Bivalent mRNA CMs showed better protection efficacy against BA.5 infection than the original mRNA CMs. On the other hand, viral replication in the respiratory region, including the lung, was strongly suppressed at 7 days post-viral infection in both groups of CMs.   

These results clearly demonstrated that current mRNA vaccines including both original and bivalent are involved in reducing the risk of COVID-19 severity, and the COVID-19 CM model is useful to consider vaccine strategy to overcome the pandemic.