Gritstone's Coral second-generation COVID-19 vaccine program evaluates the use of self-amplifying messenger RNA (SAM) and/or adenoviral vectors to deliver SARS-CoV-2 viral antigens from the spike protein of the virus, as well as other proteins outside of the spike protein.

The phase I trial is a multicenter, open-label, and dose- and age-escalation study of Coral in healthy adult volunteers. Both heterologous and homologous prime-boost vaccinations of the adenoviral vector and/or SAM vector expressing either the SARS-CoV-2 spike protein alone or the spike protein plus additional SARS-CoV-2 T-cell epitopes are being studied in a parallel design. Preliminary data from the study is expected in mid-2021.

The study is supported by the U.S. National Institute of Allergy and Infectious Diseases (NIAID) and is being conducted through the Infectious Diseases Clinical Research Consortium (IDCRC).

The company anticipates initiating a phase II trial later in 2021 examining the vaccine as a boost for people who have received a first-generation vaccine. The firm hopes that the vaccine will generate strong CD8+ T-cell responses against nonspike gene fragments, which will provide protection against SARS-CoV-2 variants.