The Coalition for Epidemic Preparedness Innovations (CEPI) and the Murdoch Children’s Research Institute (MCRI) are launching a global clinical trial to investigate the impact of administering reduced Covid-19 booster shots.
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.
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 trialled 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 programme 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.
“Over 10.4 billion doses of safe and effective Covid-19 vaccines have now been delivered worldwide, and the rollout of booster doses has dramatically ramped up in response to the cataclysmic spread of the highly infectious Omicron variant. However, despite this major progress, we continue to see a terrible chasm between rich and poor nations, with the vast majority of populations in low-income countries still waiting for their first dose, says Melanie Saville, Director of Vaccine Research & Development at CEPI.
“To prevent the further spread of this unforgiving virus and its troublesome variants, we need to achieve vaccine equity, fast. This new partnership will be key to showing us whether reduced booster dose shots could provide adequate protection against current and future variants, while also potentially showing that supplies of first doses to those in urgent need not be compromised,” says Dr Saville.
