COVID-19 Booster Study in Healthy Adults in Australia

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.

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.

Inclusion Criteria: 1. Have received three doses of COVID-19 vaccines at least 6 months earlier. 2. No confirmed SARS-CoV-2 infection on PCR or RAT within the last 3 months. 3. Willing and able to give written informed consent. 4. Aged 18 years or above. 5. Willing to complete the follow-up requirements of the study. Exclusion Criteria: 1. Currently receiving immunosuppressive medication or anti-cancer chemotherapy. 2. Known HIV infection. 3. Congenital immune deficiency syndrome. 4. Received immunoglobulin or other blood products in the three months prior to potential study booster vaccination. 5. Study staff and their relatives. 6. Have a history of a severe allergic reaction to any COVID-19 vaccines or have a medical exemption to receiving further COVID-19 vaccines. 7. Cannot read or understand English.