Sinovac: Brazil results show Chinese vaccine 50.4% effective
One of two vaccines lined up by the Brazilian government
According to recent researchers, a coronavirus vaccine developed at China's Sinovac was found to be 50.4 percent successful in Brazilian clinical trials.
It indicates that the vaccine is slightly less effective than previous data - just over 50% needed for regulatory approval.
The Chinese vaccine is one of two lined up by the Brazilian government.
Brazil was one of Covid-19's worst-affected nations.
Sinovac, a biopharmaceutical corporation located in Beijing, is an inactivated vaccine behind CoronaVac.
It operates by exposing the body' s immune system to the virus using killed viral particles without risking a significant disease response.
Several countries have placed vaccine orders, including Indonesia, Turkey and Singapore.
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Last week, researchers at the Butantan Institute, which performed the trials in Brazil, confirmed that the vaccine had a potency of 78 percent against Covid-19 "mild-to-severe"
However, on Tuesday they found that this number was not determined by data from a group of "very mild infections" for those who were vaccinated without professional support.
With this evidence being included, the effectiveness figure currently stands at 50.4%, according to researchers.
But Butantan emphasized that the vaccine is 78% effective in avoiding mild cases needing treatment and 100% effective in stopping moderate to extreme cases.
The Sinovac trials have produced varying findings in numerous countries.
Turkish researchers said 91.25% of Sinovac was successful last month, while Indonesia, which implemented its mass vaccination program on Wednesday, said it was 65.3% effective.
The interim findings from late-stage experiments were both.
Is it possible to compare vaccines?
BBC Health Reporter Philippa Roxby
The most recent statistics for China's coronavirus vaccine indicate how complicated vaccines are to compare.
On the opposite, the 50% efficacy percentage is not as strong as 70% for Oxford or 95% for Pfizer and Moderna.
However, trials in various countries are very varied - the number of registered participants vary wildly and the measures used to assess how much security the vaccines provide.
A figure of effectiveness is derived by looking at how many individuals Covid formed after the vaccine, relative to how many people were affected in the dummy injection.
It is usually focused on patients developing apparent symptoms but people with no symptoms seem to have also been involved in this Brazilian trial.
Only after the complete data of all experiments of this vaccine is released will scientists evaluate and compare their true effectiveness.
There are actually only minimal evidence available for this Sinovac vaccine and researchers agree this is troubling.
Many Covid vaccines are needed in the long run to vaccinate the planet and some will eventually do better than others, so to provide as many people as possible with some protection is a necessity.
Chinese vaccine trials have been concerned and questioned for not having been subject to the same attention and openness as their Western counterparts.
Sinovac vaccine and Oxford University vaccine, as well as the AstraZeneca pharmaceutical corporation have applications for the authorisation for emergency use pending with regulators in Brazil.
The latest news is that Brazil is seeing a big upswing.
The country currently has more than 8.1 million Covid 19 cases worldwide, just behind the US and India.
Candace Piette, editor of the BBC World Service's Americas, says the country is facing one of the worst outbreaks in the world but he has not yet announced when the vaccine campaign will launch.
The delay was largely induced by the government's haphazard policy and divided vaccination strategy, says our correspondent.