New global trial launched to study reduced-dose COVID-19 booster shots

Feb. 22, 2022

The Coalition for Epidemic Preparedness Innovations (CEPI) and the Murdoch Children’s Research Institute (MCRI) have launched a global clinical trial investigating the impact of administering reduced COVID-19 booster shots as part of efforts to increase access to COVID-19 vaccines.

Findings from the trial are expected to provide data on the potential merits of vaccinating people with fractional booster doses of COVID-19 vaccine — as opposed to a full booster dose — which could guide future COVID-19 vaccination strategies. For example, results could suggest that a reduced booster dose would improve, broaden, and prolong the immune response following a primary series of COVID-19 vaccination, while also putting less strain on first dose supplies.

The trial data could also offer crucial information as to whether fractional doses of COVID-19 vaccines produce fewer side effects in vaccine recipients following administration (compared to a full dose), which could improve the acceptability of booster doses. Additional data on administering heterologous (‘mix-and-match’) COVID-19 vaccine schedules will also be generated, CEPI said.

CEPI — part of the global COVAX initiative that encourages equitable distribution of vaccines — will provide up to US $8.7 million in funding to the global trial led by MCRI in collaboration with Padjadjaran University and the University of Indonesia in Indonesia, and the Government of Mongolia.

Researchers expect to enroll up to 3,300 healthy adults across Australia, Indonesia, and Mongolia. Depending on the trial location, participants will already have received their primary vaccination course (two doses) of either Pfizer, Oxford/AstraZeneca, Sinovac or Sinopharm COVID-19 vaccines. Participants will then receive either a full or reduced dose of one of three booster shots — Pfizer/BioNTech, Moderna or Oxford/AstraZeneca (in Indonesia). All three booster vaccines have received Emergency Use Listing (EUL) by the World Health Organization (WHO) and hold commitments to supply doses to COVAX.

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