The Coalition for Epidemic Preparedness Innovations (CEPI) in Norway and the Murdoch Children’s Research Institute (MCRI) in Australia have announced the launch of 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 important 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 will provide up to $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, and with support from the global non-profit organisation PATH. Both Indonesia and Mongolia have emerged as regional leaders in immunization and new vaccine evaluation.