The first results of an early trial of a multivariant COVID-19 vaccine booster, launched in Manchester in September 2021, has shown it is driving a comprehensive immune response.

US-based biotechnology company Gritstone bio, Inc. in collaboration with The University of Manchester and Manchester University NHS Foundation Trust today (4 January 2022) reveal the initial phase one clinical data shows the vaccine has strong levels of neutralizing antibodies, similar to approved mRNA vaccines, but at up to a 10-fold lower dose in the first 10 individuals.

Results also show the vaccine, which is being trialled with the anticipated involvement of 20 people aged 60 and over, who were in good health and previously received two doses of AstraZeneca’s first-generation COVID-19 vaccine, was generally safe and well-tolerated.

Part of Gritstone’s CORAL program, the compound is a self-amplifying mRNA second generation SARS-CoV-2 vaccine – or samRNA for short – which delivers antigens from both spike and non-spike proteins.

The samRNA vaccine also produced broad CD8+ T cell responses against targets from conserved SARS-CoV-2 viral proteins and boosted spike-specific T cells.

Based on results, the trial is now being expanded to 120 people, potentially enabling more rapid advancement into a later stage trial.

The trial is taking place within the National Institute of Health Research Manchester Clinical Research Facility (NIHR Manchester CRF) at Manchester Royal Infirmary, part of Manchester University NHS Foundation Trust (MFT). At MFT, the trial is being delivered by the Research and Innovation Vaccine Team. The trial is supported by Health Innovation Manchester.

Andrew Allen, M.D., Ph.D., Co-founder, President and Chief Executive Officer of Gritstone, said: “We are thrilled to share that our T cell-enhanced samRNA vaccine from the CORAL program is driving both robust CD8+ T cell responses to a broad array of viral epitopes and strong neutralizing antibody responses to Spike, which we believe validates the potential of our infectious disease platform.

“As we have seen with the Omicron variant, viral surface proteins such as Spike are mutating at a high rate, leaving the immunity provided by Spike-dedicated vaccines vulnerable to variants containing numerous Spike mutations. We designed our COVID-19 vaccines to drive broad CD8+ T cell immunity, an additional key layer of protection against viruses.

“This innovation enables inclusion of a wide array of highly conserved viral epitopes, potentially creating an immune state that may offer more robust clinical protection against current and future SARS-CoV-2 variants and be a first step toward developing a pan-coronavirus vaccine.”


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