What do the Sinovac coronavirus vaccine efficacy results mean?

 Questions are raised over the effectiveness of a coronavirus vaccine developed by Chinese drug maker Sinovac Biotech after a partner science institute in Brazil, where phase 3 clinical trials are under way, released lower-than-expected efficacy results for the vaccine. The Butantan Institute in Sao Paulo said the CoronaVac vaccine had a roughly 50 per cent general efficacy rate – well below the 78 per cent reported earlier. So what do the numbers mean? Is CoronaVac still effective?

The institute said the vaccine was 50.4 per cent effective in preventing Covid-19 with symptoms starting from mild to severe. The figure, which indicates how effective a vaccine is in trials, just meets the 50 per cent minimum threshold required by most regulators round the world, but is less than the 70 per cent recommended by the planet Health Organization (WHO). the ultimate efficacy rate could also be above 50.4 per cent after the corporate factors in clinical test data from Indonesia and Turkey. Turkey has said that the vaccine was found to be 91.2 per cent effective supported a smaller study.

Each trial is meant differently so direct comparisons of efficacy rates aren't possible but they're good general references in understanding the vaccine’s effectiveness.