This is a blinded, two-arm randomised study to determine the safety, reactogenicity and immunogenicity of a fourth dose of SARS-CoV-2 vaccines in Australia in adults 18 years or older who have received their third dose of COVID-19 vaccine at least six months previously. Participants will be randomised to receive either bivalent Moderna (mRNA-1273.214) or Novavax. A separate non-randomised control arm (no vaccine given), frequency matched by age to the vaccine groups will also be enrolled for comparison. A total of 200 participants per group will be recruited.
This is a double-blinded, randomised study to determine the safety, reactogenicity, and immunogenicity of a bivalent mRNA Moderna COVID-19 vaccine or a protein-based Novavax COVID-19 vaccine given as a fourth dose in healthy adults in Australia.