Sinovac vaccine 78% effective in trial in Brazil, experts ask for more details

SAO PAULO (Reuters) – A coronavirus vaccine developed by Sinovac Biotech of China was 78% effective in a late-stage Brazilian trial with no serious COVID-19 cases, researchers said Thursday, although a lack of data details calls for more transparency.

The research results, closely watched by developing countries expecting the vaccine to initiate massive vaccinations to end a raging pandemic, were lower than the preliminary findings of Turkish researchers and detailed data on US and European vaccines was lacking.

The director of Brazil’s Biomedical Center Butantan, Sinovac’s research and manufacturing partner, said detailed results were submitted to health regulator Anvisa as part of a request for emergency use of the vaccine.

“One thing is a presentation at a press conference. It’s another thing to collect and analyze the data, and that’s what Anvisa will do, ”said Cristina Bonorino, a member of the scientific committee of the Brazilian Immunology Association. “If it is what they say, that is an excellent result,” she added.

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

Although the efficacy of CoronaVac lags behind the 95% success rate of vaccines from Moderna Inc or Pfizer Inc with partner BioNTech SE, it is easier to transport and can be stored at normal refrigerator temperatures.

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

Moderna and Pfizer / BioNTech released detailed results of late-stage trials last year, before receiving emergency use authorization in the United States and elsewhere.

Butantan director Dimas Covas told a press conference that full CoronaVac data would be released in an unspecified scientific publication, but not provide a timeline.

Under pressure from journalists, Covas said there had been 218 COVID-19 cases in the trial of 13,000 volunteers. Just over 160 of those cases occurred in participants who received a placebo and the rest in vaccinated volunteers, he said.

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

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

SOME DETAILS

The fragmented disclosure of results from global CoronaVac investigations has raised concerns about the transparency of the investigations, which was not helped by Butantan’s press conference.

“It wasn’t clear or transparent,” said Denise Garrett, an epidemiologist who worked for 23 years at the US Centers for Disease Control and Prevention (CDC). “They presented secondary results on the occurrence of mild cases, severe cases and hospital admissions, but not efficacy in preventing disease.”

The partial disclosure by Butantan, who had delayed his 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 doubts its “origin”. He has traded barbs with political rival João Doria, the governor of Sao Paulo, who is funding the trials and production of the shot.

Still, Health Minister Eduardo Pazuello said on Thursday that the federal government would buy Butantan’s entire production of CoronaVac this year, which is nearing a deal to buy 100 million doses for a national immunization program.

Brazil has the world’s second-deadliest outbreak after the United States, with a death toll exceeding 200,000 on Thursday, and aims to vaccinate 51 million people, or about a quarter of the population, by the first half of 2021. [nL1N2JI32B]

Vaccinations have not yet started. Doria reiterated that Sao Paulo, the country’s most prosperous and densely populated state, was expected to begin vaccinations on January 25.

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 be stable for up to three years.

Vaccines offered by Pfizer / BioNTech and Moderna use a new synthetic messenger RNA (mRNA) technology, which requires much colder temperatures for shipping and storage. The Pfizer / BioNTech vaccine must be stored at a sub-arctic temperature, making it an ineffective option for poor countries and areas without the required cold storage equipment.