Sinovac vaccine performs at 83.5% in Phase Three trial

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New data from Phase Three of the Sinovac vaccine trial shows that the drug is now performing at 83.5%

When Phase Two data dropped for Sinovac, it appeared to be 50.4% efficient against COVID-19. Now, the percentage is up to 83.5% with interim data from Phase Three of clinical trials.

In this latest trial, participants were given two doses of Sinovac, 14 days apart.

From 14 days after the second dose, 9 cases of symptomatic COVID-19 were confirmed in the vaccine group, an incidence rate of 32 cases per 1,000 people per year. In the placebo group, 32 cases were reported, an incidence rate of 192 cases per 1,000 people per year. Following analysis, the authors estimate that this is equivalent to a vaccine efficacy of 83.5%.

Sinovac Life Sciences developed the vaccine, also known as CoronaVac, using an inactivated whole virus. The body responses by attacking this harmless form of the virus by producing antibodies to fight it off, leading to immunity. Sinovac can also be stored and transported at 2-8°C, making it a prime candidate for use in countries without cold transport infrastructure at the ready.

‘It does not need to be frozen’

Lead author Professor Murat Akova, from Hacettepe University Medical School, Turkey, said: “In order to bring the COVID-19 pandemic under control, the world needs every single dose of safe and effective vaccines, and our results add important evidence of the safety and effectiveness of inactivated-virus vaccines. One of the advantages of CoronaVac is that it does not need to be frozen, making it easier to transport and distribute.

“This could be particularly important for global distribution, as some countries may struggle to store large amounts of vaccine at very low temperatures.”

Were there any side effects in the trial?

No severe adverse events or deaths were reported among the more than 10,000 trial participants in Turkey, with most adverse events mild and occurring within 7 days of an injection.

At the moment, it is not known how effective the Sinovac vaccine would be against variants of concern that are emerging – or variants of interest, like Lambda. 


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