China’s Sinovac delays results of Covid-19 vaccine trials

SÃO PAULO – The Chinese company Sinovac Biotech Ltd. has delayed the announcement of results from late-stage trials of the Covid-19 vaccine until January, as it consolidates data from Brazil with test results from Indonesia and Turkey.

Brazil, the first country to conduct Phase 3 trials with CoronaVac, had expected to announce the vaccine’s efficacy on Wednesday. However, Brazil’s Butantan Institute, the research center backed by São Paulo’s state government that has tested CoronaVac, Sinovac asked for another 15 days to analyze the data along with results from other vaccine trials, which are also being tested in Indonesia and Turkey.

“There can be no three efficacy results for the same vaccine,” said Butantan’s director Dimas Covas. He said the delay had nothing to do with the effectiveness of the vaccine, which is expected to be one of the first approved for use in Brazil.

Researchers tracking the vaccine had hoped that CoronaVac could be compared to other Covid-19 vaccines, which have been shown to be as much as 95% effective.

A protester is taking part in a protest calling for a Covid-19 vaccine and against Brazilian President Jair Bolsonaro in Brasilia on Wednesday.


ueslei marcelino / Reuters

“It was very frustrating … this is the only vaccine we currently have on Brazilian soil,” said Luiz Carlos Dias, part of a Covid-19 task force of researchers at the University of Campinas in the state of São Paulo. “I’m worried that the efficiency may not be that high.”

Other researchers said they were not concerned and dismissed the delay as a purely contractual issue. “It’s an anticlimax, it must have happened because Sinovac forbade them to announce the result, very likely because it’s just the result of a country,” said Carlos Fortaleza, an epidemiologist at São Paulo State University.

While Mr Covas said he could not communicate the results of the trial, he said CoronaVac had passed the 50% efficiency threshold, meaning regulators could give the green light for use.

The Wall Street Journal did not report until Monday that Phase 3 results showed that CoronaVac had exceeded the 50% threshold set by international researchers for a vaccine to be considered viable.

Sinovac, a private company in Beijing that has also developed vaccines against hepatitis A and B, H5N1 avian influenza virus and H1N1 swine flu virus, did not immediately respond to requests for comment.

As the disease is largely under control at home, China’s vaccine manufacturers have approached other countries to conduct their clinical trials.

Brazil has proven to be an ideal test site. Covid-19 has ravaged the Latin American country, killing nearly 190,000 people, second only to the United States

Sir. Covas said more than 200 of the Phase 3 trial volunteers were contracted to Covid-19, allowing researchers to calculate CoronaVac’s efficacy rate by seeing how many of these people took the vaccine or placebo. To get final results, researchers waited for at least 154 volunteers to take Covid-19, but the number was quickly surpassed as the disease returned roaring in Brazil in recent weeks after previous falls.

Trials with CoronaVac in Turkey and Indonesia are still ongoing.

Brazilian infectious disease specialists tracking CoronaVac’s have hoped for results similar to those developed by Moderna Inc.

and together by Pfizer Inc.

and BioNTech SE, which have been shown to have an efficiency rate of 94.5% and 95%, respectively, in the final test phases. Unlike these two vaccines, new types of genetic code vaccines, CoronaVac is one of many traditional virus-based vaccines that use a killed or attenuated form of the targeted virus to induce an immune response.

While these more traditional vaccines tend to have lower efficacy rates, CoronaVac can be stored in a standard refrigerator between approx. 36 and 46 Fahrenheit, making it easier to transport and store in poor and less developed countries, said infectious disease specialists.

The government of São Paulo plans to use the vaccine to immunize the state, home to a fifth of Brazil’s population, by the end of July. Butantan also plans to ship CoronaVac in May to Argentina, Bolivia, Colombia, Honduras, Peru and Uruguay.

“It is much easier logistically to bring the vaccines in from Brazil than from China,” Colombian Health Minister Fernando Ruiz said in an interview. Like most countries in the region, Colombia lacks the capacity to produce its own vaccines. The Philippines has also been in talks with Sinovac.

Write to Samantha Pearson at[email protected] and Luciana Magalhaes at [email protected]

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