A few days ago, SinoVac's phase three of vaccine clinical trials were halted in Brazil due to a serious adverse event to one volunteer on October 29. At the same time, the company clarified in a statement that the case was unrelated to the vaccine but released no further details.

However, a police report indicated that the volunteer died by suicide. Investigations of the cause of death as well as a toxicology report are ongoing.

Meanwhile, Anvisa, Brazil's National Health Surveillance Agency, is allowing SinoVac to resume clinical trials. The agency also concluded that "there are sufficient benefits to allow the vaccination to resume." They are monitoring the ongoing investigation between the vaccine trials and the unexpected serious adverse event.

Clinical trial interruptions are not uncommon, experts explain. A similar case occurred in September when one UK volunteer of the AstraZeneca/Oxford vaccine clinical trials developed an unexplained illness.

After it was confirmed that the volunteer's illness was unrelated to the vaccine, trials continued in all testing sites except in the United States. A month later, a Brazilian volunteer died, but trials continued since it was confirmed that the patient was part of the control group who received a dose of meningitis and not the vaccine candidate.

Johnson & Johnson's vaccine trials were also paused in early October after a volunteer suffered a stroke. However, investigations identified no clear evidence that the stroke was triggered by the vaccine. J&J's vaccine trials have also resumed a few weeks after.

Phase Three Trials Protocol

SinoVac continues to communicate with their partner in Brazil, the Butantan Institute, regarding vaccine trials, claimed the company. The institute originally targeted to recruit 9,000 volunteers but resulted in 13,000 recruits. The protocol of phase three trials have been published in the journal Trials.

In the randomized, double-blind, placebo-controlled trials, volunteers will be divided into two groups: those between 18 and 59 years old and 60 years old and above. They will all receive two intramuscular doses of the CoronaVac or a placebo with a 14-day interval.

CoronaVac is made from inactivated coronavirus with an aluminum hydroxide adjuvant. Adjuvants make vaccine immunity more robust and prolonged. The placebo is a mixture of solution and aluminum hydroxide.

Read Also: Sinovac 99% Confident that 'CoronaVac' Will Work Effectively Against Coronavirus

"Safest Vaccine" In Brazil

The World Health Organization and Food and Drug Administration consider a vaccine efficacious if it has a protection level of 50% in phase three clinical trials. "The clinical study in Brazil is strictly carried out in accordance with GCP (Good Clinical Practice) requirements and we are confident in the safety of the vaccine," stated the Chinese company.

While the Brazillian president has openly expressed that he is against China's vaccine, Governor Joao Doria from Sao Paulo and the head of Butantan Institute said that CoronaVac is the safest vaccine being tested in the country. Once approved, SinoVac said they would provide Brazil with 60 million doses before the end of the year.

Read Also: China Already Has Several Vaccine Candidates For Public Use

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