The Sinovac vaccine is 78% effective in a trial in Brazil. Experts are asking for more details

SAO PAULO (Reuters) – A coronavirus vaccine developed by China’s Sinovac Biotech was 78% effective in a Brazilian final-stage trial without severe COVID-19 cases, researchers said on Thursday, despite the lack of data details led to greater transparency.

The results of the trial, closely monitored by developing countries that relied on the vaccine to initiate mass inoculations to help end a rapid pandemic, were below the preliminary results of Turkish researchers and had no detailed data on vaccines. American and European.

The director of the Brazilian biomedical center Butantan, Sinovac’s research and production partner, said detailed results were presented to health regulator Anvisa as part of an urgent use of the vaccine.

“One thing is a presentation at a press conference. It is another thing to obtain the data and analyze them, which is what Anvisa will do, ”said Cristina Bonorino, who is part of the scientific committee of the Immunological Society of Brazil. “If that’s what they say, it’s an excellent result,” he added.

Brazil and Indonesia, which have the most cases of COVID-19 in Latin America and Southeast Asia, respectively, are preparing to launch the vaccine, called CoronaVac, this month. Turkey, Chile, Singapore, Ukraine and Thailand have also signed supply agreements with Sinovac.

Although the effectiveness of CoronaVac is less than the 95% success rate of Moderna Inc or Pfizer Inc vaccines with BioNTech SE partner, it is easier to transport and can be stored at normal refrigerator temperature.

The 78% efficacy rate is also well above the 50% to 60% benchmark set by global health authorities for vaccines in development at the beginning of the pandemic, given the urgent need.

Moderna and Pfizer / BioNTech published the detailed results of end-of-phase trials last year, before receiving emergency use permits in the United States and elsewhere.

Butantan director Dimas Covas said at a news conference that the full CoronaVac data would be published in an unspecified scientific publication, but that it did not provide a timeline.

Pressed by reporters, Covas said there had been 218 COVID-19 cases in the trial of 13,000 volunteers. Just over 160 of those cases occurred among participants who received a placebo and the rest were in vaccinated volunteers, he said.

Unlike other vaccine studies, the CoronaVac study in Brazil included elderly volunteers, a particularly vulnerable population.

Covas said CoronaVac had completely prevented serious cases of COVID-19 among the vaccinated group, including the elderly. None of those who received the vaccine get sick enough to require hospitalization, he added.

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The partial disclosure of CoronaVac’s global study results has raised concerns about the transparency of the trials, which did not help the Butantan press conference.

“It was neither clear nor transparent,” said Denise Garrett, an epidemiologist who worked for 23 years at the U.S. Centers for Disease Control and Prevention (CDC). “They presented secondary outcomes in the prevention of mild, severe cases and hospitalizations, but not efficacy in disease prevention.”

Butantan’s partial disclosure, which had delayed its announcement three times, citing obligations to Sinovac, added to skepticism about the Chinese vaccine in Brazil. According to a December poll, nearly half of Brazilians said they would not take a COVID-19 vaccine developed by China.

Brazilian President Jair Bolsonaro has expressed contempt for the Sinovac vaccine and expressed doubts about its “origin.” He has changed his mind with political rival João Doria, the governor of Sao Paulo, who is funding the rehearsals and production of the shot.

However, Health Minister Eduardo Pazuello said on Thursday that the federal government would buy total production of CorantanVac from Butantan this year, on the verge of reaching an agreement to buy 100 million doses for a national vaccination program. .

Brazil has the second deadliest outbreak in the world after the United States, with a death toll that exceeded 200,000 on Thursday and aims to vaccinate 51 million people, or about a quarter of its population, during the first half of the year. 2021. [nL1N2JI32B]

Vaccinations have not yet begun. Doria reiterated that Sao Paulo, the richest and most populous state in the country, was expected to begin vaccinations on January 25th.

Based on traditional vaccine technology that uses inactivated coronavirus to elicit an immune response, CoronaVac can be stored at temperatures of 2-8 degrees Celsius (36 ° -46 ° F) and can remain stable for up to three years.

The vaccines offered by Pfizer / BioNTech and Moderna use a new synthetic messenger RNA (mRNA) technology that requires much colder temperatures for sending and storage. The Pfizer / BioNTech vaccine should be kept at a subarctic temperature, making it an ineffective option for nations and poor areas without the necessary cold storage equipment.