BEIJING – Nasdaq-listed Chinese vaccine developer Sinovac Biotech Ltd., of Beijing, said the preliminary results of the phase I/II trials of its COVID-19 inactivated vaccine candidate, Coronavac, demonstrated favorable immunogenicity and safety profiles. The company told BioWorld that it aims to move it to phase III trials outside China next month.

The positive results were unveiled less than two months after the study started. Sinovac said it will unveil the full data in academic publications as soon as possible.

“Our phase I/II study shows Coronavac is safe and can induce immune response,” said Sinovac CEO Weidong Yin.

The randomized, double-blind and placebo-controlled phase I/II trials enrolled a total of 743 healthy volunteers, ages 18 to 59, in which 143 volunteers were in the phase I trial and 600 in the phase II trial. Sinovac said there were no severe adverse events, but only grade I adverse events such as mild pain, fatigue and low fever.

Results from the phase II trial showed the vaccine candidate induced neutralizing antibodies 14 days after inoculation. The seroconversion rate of the neutralizing antibody was above 90%, which led Sinovac to conclude that the vaccine can induce a positive immune response.

On April 16, Sinovac initiated the phase I trial, three days after it received approval from China’s NMPA, and then moved the candidate to phase II trials in May. Work on developing the vaccine began on Jan. 28.

Encouraged by the positive preliminary results, the company is working to spearhead the vaccine’s development. It plans to submit a phase II study report and a phase III trial protocol to the NMPA soon.

“We aim to conduct the phase III trial next month,” Pearson Liu, Sinovac’s director of brand management and public relations, told BioWorld. “We plan to conduct the phase III trials in countries that see a high incidence of COVID-19, so at this stage China is not an option for us since the incidence rate is low.

“We will submit the phase III trial protocol to the NMPA and to its counterparts in other countries to obtain the trial approval,” he said, adding that Brazil is one of the options for a location to carry out the late-stage trials.

On June 11, Sinovac unveiled a partnership with Instituto Butantan, a Sao Paulo-based immunobiologic producer, to advance the clinical trial of the vaccine to phase III trials. Instituto Butantan will sponsor the trials in Brazil. The two are continuing talks to establish a collaboration for technology licensing, market authorization and commercialization of the vaccine candidate to bring it to the Brazilian population.

As of Monday, Brazil saw around 868,000 confirmed cases, up by more than 320% from a month ago.

Targeting global use

Sinovac is also gearing up its manufacturing capability to meet the massive unmet demand. It is constructing a commercial vaccine production plant in China that could pump out up to 100 million doses of the COVID-19 vaccine yearly.

“We have started to invest in building a manufacturing facility so that we can maximize the number of doses available to protect people from COVID-19,” said CEO Yin. “Like with our other vaccines, we are committed to developing Coronavac for global use.”

Prior to the phase I/II study, Sinovac published preclinical results in Science that showed the vaccine candidate is safe and does not produce side effects in monkeys. In that trial, eight rhesus macaques were vaccinated with two different doses (3μg or 6 μg per dose) and none developed a full-blown infection three weeks after researchers introduced SARS-CoV-2 into their lungs. That led to the company’s belief that its vaccine candidate could provide protection against COVID-19.

Sinovac’s vaccine development has been receiving full support from both the Chinese government and private investors. Multiple government agencies back the project, such as the Ministry of Science and Technology, the National Health Commission, the NMPA, the Zhejiang Provincial Center for Disease Control and Prevention (CDC), The Institute of Laboratory Animal Sciences at Chinese Academy of Medical Sciences and China’s CDC.

On the capital front, the company received $15 million from Advantech Capital and Vivo Capital to advance the vaccine’s development on May 22.

"We … appreciate the support of Advantech Capital and Vivo Capital as well as cooperation from all levels of the Chinese government, who have been essential in allowing us to move forward at full speed with the development of Coronavac without compromising our high safety standards and procedures,” said Yin.

Inactivated vaccines target the whole virion. Researchers noted in a report in Cell that it can be relatively easy to develop those vaccines since they are developed through a straightforward process by using the existing infrastructure.

Sinovac has been using that technology to develop multiple vaccines. It has developed vaccines for hepatitis A and B, swine flu, avian flu, and the virus that causes hand, foot and mouth disease.

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