Beijing-based Sinovac Life Sciences Co announced on Monday that its COVID-19 vaccine collaboration with Brazilian immunobiologic producer Instituto Butantan has received approval from the Brazilian regulator for phase III clinical trials.

The Brazilian National Regulatory Agency, Anvisa, granted approval to a phase III clinical trial sponsored by Instituto Butantan on Friday to test the efficacy and safety of the inactivated COVID-19 vaccine developed by Sinovac Life Sciences Co in Brazil. This trial aims to be a pivotal study to support the licensing of the product, according to an official statement the company sent to the Global Times.

The trial will recruit nearly 9,000 healthcare professionals to work in COVID-19 specialized facilities in 12 clinical sites in several states in Brazil. The recruitment is scheduled to start this month after ethical approval is obtained from each clinical site.

The study will be a double-blind placebo-controlled trial with participants randomly allocated a 1:1 ratio of placebo and vaccine, according to the announcement from Instituto Butantan on Thursday.

The immunization schedule is two doses of intramuscular injections (deltoid) with a 14-day interval, it said.

For efficacy, the study aims to detect COVID-19 cases, defined as symptomatic SARS-CoV-2 infections, after the second week post-immunization schedule.

For safety and immunogenicity, participants are categorized in two age groups, adults (18-59 years) and elderly (60 years and above). All participants will be followed for up to 12 months.

Anvisa reviewed the detailed manufacturing information, the results of the previous two clinical trials of the vaccine candidate, and late-stage trial protocols developed by Instituto Butantan. It took only about two weeks for the agency to fast-track the application due to the public health emergency.

The review was conducted at the highest standards and met with international rules. Anvisa is qualified as a fully functional regulatory agency for the WHO prequalification process. The agency is also a full member of the International Council for Harmonization of Technical Requirements for Pharmaceuticals for Human Use (ICH), according to the statement.

"The phase III clinical trial approval is a demonstration that the Sinovac and Instituto Butantan partnership is an efficient collaboration, offering hope to save lives worldwide," commented Dr Dimas Covas, director of Instituto Butantan.

"We are pleased to advance to Phase III trials with Instituto Butantan, which will take us one step further in our commitment to develop vaccines for global use and our mission of supplying vaccines to eliminate human diseases," Weidong Yin, chairman, president and CEO of Sinovac, commented in the statement.

Sinovac announced on June 13 positive preliminary results in Phase I/II clinical trials for the inactivated vaccine, which showed favorable immunogenicity and safety profiles.

The Phase II results showed that the vaccine induces neutralizing antibodies within 14 days. The neutralizing antibody seroconversion rate is above 90 percent.

Brazil has become a new epicenter of the pandemic. The country has reported more than 1,600,000 confirmed COVID-19 cases as of Monday.

The cooperation is expected to achieve a win-win outcome as a vaccine can help end the grim epidemic in Brazil. China, in contrast, has become less favorable as a late-stage clinical trial hub, given its smaller number of new cases.

The two parties aim to establish extensive collaboration in technology licensing, market authorization and commercialization of the vaccine, according to an announcement Sinovac sent to the Global Times on Tuesday.

On June 29, Sao Paulo state Governor Joao Doria said 9,000 volunteers have already been registered to test the vaccine against COVID-19, Reuters reported.

Instituto Butantan will spend 85 million reals ($17.1 million) to conduct trials on 9,000 Brazilian volunteers, the governor said, adding that if the vaccine proves effective, it could be mass-produced in São Paulo, starting from the first half of next year, and administered to millions of Brazilians free of charge.

The company has partnered with several companies outside of China for phase III efficacy studies, Sinovac told the Global Times.