Bringing Optimised COVID-19 Vaccine Schedules To ImmunoCompromised Populations (BOOST-IC): an Adaptive Randomised Controlled Clinical Trial

Despite the greater risk of adverse COVID-19 outcomes, antibody and cell-mediated immune responses to COVID-19 vaccines vary amongst immunocompromised (IC) people and are poorly defined. IC hosts were largely excluded from the COVID-19 vaccine registration trials, though many countries recommend additional and booster doses of vaccination in this group. However, data are heterogeneous, in part due the variable nature of immunodeficiencies in IC groups and non-standardised outcome measures used in studies. BOOST-IC is an adaptive randomised clinical trial (RCT) to assess the immunogenicity and safety of additional bivalent COVID-19 vaccine doses in immunocompromised (IC) people, including people with HIV, solid organ transplants (SOT) recipients or those with haematological malignancies. Briefly, the study aims to generate high-quality evidence on the immunogenicity and safety of alternative COVID-19 booster strategies against SARS-CoV-2 for IC people in Australia. To do this, participants who have previously completed 3- to 8-doses of Australian TGA approved COVID-19 vaccines (Moderna and Pfizer vaccines) will be randomised 1:1 to receive either one or two doses of the current TGA approved COVID-19 vaccine. .An additional arm can be added if an additional suitable vaccine becomes available. Namely, patients will be randomised to receive either one or two doses of Moderna or Pfizer COVID-19 vaccine. As additional COVID-19 vaccines become available in Australia, these will be included in the trial, as additional arms. The trial can incorporate up to three arms at one time. Patients will be followed up for 455 days post randomisation. Specific study questions pertain to: * examining how additional doses of COVID-19 vaccine/s affect correlates of protective immunity * examining the safety of additional doses of COVID-19 vaccine/s * characterising the humoral and cellular immune responses to COVID-19 vaccination receiving 1 or 2 booster doses of COVID-19 vaccine/s