Sinovac's Covid-19 vaccine efficacy less than 60% in Brazil trial

SAO PAULO (REUTERS) – The coronavirus vaccine developed by China’s Sinovac Biotech showed a general efficacy of less than 60 per cent in its late-stage trial in Brazil, a news website reported on Monday (Jan 11), citing two people who seen the results.

Sao Paulo’s Butantan biomedical centre, which partnered with Sinovac to test and produce the vaccine in Brazil, dismissed the report as “purely speculative” as it prepares to release a more complete set of results on Tuesday at 12.45pm.

Medical experts and regulators criticized what they called an incomplete disclosure of study results last week.

Dimas Covas, director of the Butantan biomedical centre, which is running a late-stage trial of the vaccine in Brazil, said ongoing analysis had yielded a new “general efficacy” rate in addition to the “clinical efficacy” announced last week.

On Thursday, Brazilian researchers said the vaccine was shown to be 78 per cent effective against mild cases of Covid-19 and entirely prevented severe cases. But independent specialists called for more transparency on the findings from the phase three trial of the Sinovac vaccine, known as CoronaVac.

Indonesia gave the vaccine emergency use approval on Monday based on interim data showing it is 65 per cent effective.

Brazilian news website UOL reported that the efficacy rate that Butantan was set to announce on Tuesday was between 50 per cent and 60 per cent – above the threshold set by health regulators, but well below the numbers celebrated last week.

Both the Chinese vaccine and a shot developed by Oxford University and British-Swedish firm AstraZeneca Plc have requests for emergency use authorization pending with regulators in Brazil, which has lost more than 200,000 lives to the pandemic – the worst death toll outside the United States.

Piecemeal disclosure of results from global CoronaVac studies have contributed to concerns that vaccines developed by Chinese producers are not subject to the same public scrutiny as US and European alternatives.

In an interview with news website UOL on Monday, Covas said Butantan, which is funded by Sao Paulo state, had prioritized getting its data to Brazilian health regulator Anvisa and was still analysing the results in parallel.

Covas said the institute would eventually provide its full data to a scientific conference to be announced this week.

Anvisa said on Saturday that a filing from Butantan seeking emergency use authorization for CoronaVac lacked some relevant information for analysis of the study, such as the age, gender and comorbidities of volunteers.

Covas said the federal agency’s handling of the CoronaVac trial had raised questions about its independence, adding to tensions between Sao Paulo officials and the government of President Jair Bolsonaro, who had spurned the Chinese vaccine.

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