New global vaccine trial launched to evaluate fractional COVID-19 booster shots

Feb. 22, 2022

The Coalition for Epidemic Preparedness Innovations (CEPI) and the Murdoch Children’s Research Institute (MCRI) 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 US $8.7 million (AU $12.3million) 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 organization PATH. Both Indonesia and Mongolia have emerged as regional leaders in immunization and new vaccine evaluation.

Up to 3300 healthy adults will be invited to take part in the trial 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 being trialed have received Emergency Use Listing (EUL) by the World Health Organization (WHO) and hold commitments to supply doses to COVAX.

Launch of the CEPI-MCRI research program follows a recent statement made by the WHO urging broader global access to COVID-19 vaccines for both primary vaccinations and booster doses to maintain COVID-19 immunity in light of the emergence and impact of new variants like Omicron.

While the rollout of booster doses continues to accelerate in many high-income countries, populations in many low-income nations are still waiting for their first COVID-19 vaccine dose, resulting in a serious imbalance in global protection. Administering reduced vaccine shots—also known as fractionation—has previously been used to maximize global vaccine supply during outbreaks of Yellow fever and Polio. MCRI also last month published supportive research for this dose-sparing strategy for the experimental rotavirus vaccine, RV3-BB.

CEPI release

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