The study involves a novel, self-amplifying mRNA vaccine against COVID-19 that delivers antigens from both the spike and non-spike proteins

covid vaccination

A clinical trial of a novel COVID-19 vaccine, that could boost the immune response generated by existing COVID-19 vaccines and help combat variants of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has been launched in the UK.

US pharmaceutical company Gritstone has partnered with the National Institute for Health Research (NIHR) Manchester Clinical Research Facility to evaluate the effectiveness of the vaccine, called GRT-R910.

The candidate vaccine is a self-amplifying mRNA (SAM)—a second-generation SARS-CoV-2 vaccine that delivers antigens from both the spike and non-spike proteins.

SAM vaccines work by inducing CD8+ T cells, as well as antibodies.

The manufacturer hopes the phase-I trial, involving 20 volunteers aged 60 years and over, can demonstrate the vaccine’s potential to neutralise the virus and prevent it binding to and infecting cells.

The ambition is to offer the potential for robust and persistent immunity, particularly in at-risk groups and older people.

‘Strong, durable, and broad immune responses’ 

Professor Andrew Ustianowski, Clinical Lead for the NIHR COVID-19 vaccine research programme and lead investigator for the study, said: ‘We now know the immune response to first-generation vaccines can wane, particularly in older people. Coupled with the prevalence of emerging variants, there is a clear need for continued vigilance to keep COVID-19 at bay.’

He believes that the GRT-R910 booster vaccination has the potential to produce ‘strong, durable, and broad immune responses’.

The study will examine the dose, safety, tolerability, and immunogenicity of GRT-R910 at two dose levels given at least 4 months after participants had a second dose of an initial COVID-19 vaccine.

Dr Andrew Allen, President of Gritstone, said: ‘Since viral surface proteins like the spike protein are evolving and sometimes partially evading vaccine-induced immunity, we designed GRT-R910 to have broad therapeutic potential against a wide array of SARS-CoV-2 variants by also delivering highly conserved viral proteins that may be less prone to genetic variation in the virus.

‘Our hypothesis is that a different vaccine such as GRT-R910 might complement the primary immune response from pre-existing vaccination with a first generation COVID vaccine in such a way that it would provide more benefit than an additional dose of the same vaccine.’

Andrew Clarke and his wife Helen from Bolton, who are both in their 60s, were the first to receive the vaccine.

Helen said: ‘We’ve been amazed how quickly a vaccine was made and approved and that couldn’t happen without volunteers’.

Andrew added: ‘Somebody has to be the first and we’re confident in the science and technology behind this vaccine and convinced of the need for it’.

The trial will take place at Manchester Royal Infirmary, part of Manchester University NHS Foundation Trust.

GRT-R910 is also being investigated as part of a US National Institute of Health sponsored phase-I study.

Booster vaccines 

The trial comes as findings from a new Scottish study support offering a third or ‘booster’ vaccine dose to people previously on the shielding list who are known to be clinically extremely vulnerable to COVID-19.

The study, published as a preprint, led by Public Health Scotland and the University of Edinburgh, found that people previously in this group had 66% protection against severe COVID-19 disease after two doses of any COVID-19 vaccine, compared with 93% protection in those without high-risk conditions.

Earlier this month, the Joint Committee on Vaccination and Immunisation (JCVI) recommended a booster vaccine for people who are immunosuppressed.

Dr Nick Phin, Director of Public Health Science at Public Health Scotland, said: ‘The findings of this study confirm that all the vaccines approved for use in the UK continue to be highly effective at reducing severe illness and death from COVID-19.

‘Whilst those who are clinically extremely vulnerable get, on average, a substantial level of protection to COVID-19, it will vary from person to person and by the nature of their vulnerability. We therefore welcome the JCVI advice and the subsequent rollout of the programme that prioritises a third dose for those who are known to be at most risk from COVID-19.’

This article originally appeared on Medscape, part of the Medscape Professional Network.


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