A Randomised, Double-Blinded, Positive Controlled Phase IIb Clinical Trial to Evaluate the Immunogenicity and Safety of COVID-19 Vaccine (Vero Cell), Inactivated Booster Dose in Adults who have completed two doses of CoronaVac or VaxzevriaTM in Indonesia (PRO-nCOV-2006)

Funders: SinoVac Life Sciences
Principal Investigators: Robert Sinto, Raph Hamers
Location of activity: Jakarta
Collaborators: Faculty of Medicine. Universitas Indonesia,Jakarta Health Agency

Vaccine-induced population immunity is a key global strategy to control the
COVID-19 pandemic, and to date eight COVID-19 vaccines have received
Emergency Use Listing (EUL) by the WHO. Accumulating evidence shows a
progressive increase in breakthrough infections after a two-dose vaccine schedule
associated with diminishing humoral immunity over time. Neutralisation and
vaccine effectiveness after two-dose vaccine schedules are particularly reduced
for the recently emerged Omicron variant (B.1.1.529), with significant restoration
after a third vaccine booster dose. CoronaVac (SinoVac Life Sciences Co Ltd,
Beijing, China), an inactivated whole-virus vaccine that received WHO EUL on
June 1st, 202118, is currently one of the most widely administered COVID-19
vaccines worldwide with around 2 billion in 54 countries, as per February, 2022,
and the predominant vaccine in Indonesia.
As policy makers in several countries have started implementing third or periodic
boosting to protect the most vulnerable populations, and mitigate health care and
economic impacts, further clinical trial data and cohort studieswill be are critical
to guide decisions regarding when, which populations and what boosters should
be administered. Recent trials suggested that heterologous (or “mix and match”)
virus-vectored or mRNA booster strategies were more immunogenic than a
homologous schedule, albeit with increased reactogenicity in some combinations.
There are still insufficient data on the efficacy and efficacy persistence of a
CoronaVac booster immunisation after primary vaccination with CoronaVac or
Vaxrevia, and whether a double-dose booster could enhance immunogenicity.
The present study is designed to evaluate the immunogenicity of a third booster
dose of CoronaVac among adults aged 18 years and above, after primary
vaccination with CoronaVac or Vaxrevia, given in a medium-dose (currently
approved) or full-dose (600 SU/0.5 ml and 1200 SU/0.5 ml, respectively).

Primary: To evaluate the immunogenicity of a high or medium dosage inactivated
booster vaccine
• To evaluate immune persistence of a high or medium dosage inactivated
booster vaccine
• To evaluate the safety of a high or medium dosage inactivated COVID-19
booster vaccine
• To evaluate cellular immune responses of a high or medium dosage inactivated
COVID-19 booster vaccine
• To evaluate incidence and genetic variants of COVID-19 breakthrough