China-based biopharmaceutical company Sinovac Biotech has started Phase III clinical trial of its inactivated Covid-19 vaccine candidate, CoronaVac, in Turkey.

The pivotal study will assess the safety and efficacy of the vaccine candidate and is intended to support the licensure of the product in Turkey.

With an adaptive design, the case-driven, randomised, double-blinded, placebo-controlled Phase III trial will recruit volunteers in a step-by-step approach.

The first stage of the study will involve 1,300 healthcare workers aged 18-59 years who will be administered two doses of the vaccine candidate or placebo at a two-week interval.

In the second stage, about 12,000 individuals of the general population aged 18-59 years will be randomised to receive two CoronaVac or placebo doses at a two-week interval.

The company has already performed Phase I/II studies of the vaccine in volunteers aged 18-59 years and those aged 60 years old and above, at Jiangsu and Hebei Provinces on 16 April and 22 May, respectively, in China.

China’s National Medical Products Administration (NMPA) granted approval for Sinovac to perform the Phase I/II trials in the country. These trials were designed to assess the vaccine candidate’s safety, tolerance, dosage and immunisation schedule.

Phase I/II data showed that CoronaVac was well tolerated at different dosages, without any serious vaccine-related adverse events. Sinovac said that the potential Covid-19 vaccine demonstrated a good safety profile.

Seroconversion rates in both adults and elderly subjects were higher than 90%, indicating favourable immunogenicity of the product, added the company.

Turkey has also collaborated with various companies outside of China for Phase III efficacy studies.

In July this year, the Brazilian National Regulatory Agency, Anvisa, granted approval to carry out a Phase III trial sponsored by Instituto Butantan to test CoronaVac.

Sinovac partnered with Instituto Butantan earlier in June to conduct the Phase III study.

Meanwhile, Sinovac is building a commercial vaccine manufacturing plant in China with an aim to produce up to 100 million doses of CoronaVac each year.