A COVID-19 vaccine booster aimed at tackling multiple coronavirus variants shows promise in inducing a comprehensive immune response, early data suggests.
The initial phase one clinical data shows the vaccine has strong levels of neutralising antibodies, similar to approved mRNA vaccines, but at up to a 10-fold lower dose in the first 10 individuals.
The yet-to-be peer-reviewed results also show the vaccine, being trialled with the anticipated involvement of 20 people aged 60 and over, was generally safe and well-tolerated.
The trials are being conducted by US-based biotechnology company Gritstone bio in collaboration with the University of Manchester and Manchester University NHS Foundation Trust.
The self-amplifying mRNA second generation SARS-CoV-2 vaccine -- or samRNA -- delivers antigens from both spike and non-spike proteins.
The spike protein is used by the SARS-CoV-2 virus to enter and infect human cells, and is a target of most currently used vaccines.
The samRNA vaccine also produced broad CD8+ T cell responses against targets from SARS-CoV-2 viral proteins and boosted spike-specific T cells.
T cells are part of the immune system, and form the second line of defence beyond antibodies.