COVID-19: China's Sinovac vaccine shows four efficacy rates, experts concerned

While its global rollout has kicked in with multiple South East Asian nations looking to expedite inoculation, uncertainty continues to swirl over the efficacy of the leading Chinese shot. With a tentative cost of INR 1,027, the Sinovac shot has shown four different efficacy rates during clinical trials ranging from over 91 to 50 per cent. While Sinovac jab has already been approved by the Chinese regulators for vaccinating general public, the scientific community is still sceptical about its global use.

Varied efficacy rates

Indonesia, wherein President Joko Widodo kick-started the inoculation drives by receiving the shot on Live television, had previously said that a local trial showed an efficacy of 65 per cent against Covid-19. However, the rate was dismissed as the trial involved only 1,650 people. Turkey, which conducted a local trial starting September, said that the Chinese vaccine was 91.25 per cent effective. However, this too was dismissed saying that the trials were too small, that is less than 50 people.

Meanwhile, in Brazil, where a final phase trial on more than 13,000 people is being conducted, duelling efficacy rates have been publicized. The company’s local trial partner, Butantan Institute, last week, concluded that the vaccine was 78 per cent effective in preventing mild cases of Covid-19 and 100% effective against severe and moderate infections. However, later it said that overall rate, which also includes very mild cases that didn't require medical help, is actually 50.38 per cent.

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In contrast, Sinovac Biotech has stood by the safety of its vaccine and said it is confident that its candidate vaccine was safe. In a statement, Sinovac had said that the firm is “confident in the safety of its vaccine”. The Chinese company added that the “adverse incident” was “unrelated” to CoronaVac. 

In November, the Brazilian regulator, Anvisa, reportedly said that it had ruled to interrupt the clinical trial of the CoronaVac vaccine after a “serious adverse incident”. According to local media reports, the National Health Surveillance Agency said that it could not give details on what happened, but added that such incidents included death, potentially fatal side effects, serious disability, hospitalisation, birth defects and other “clinically significant events”. 

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