A Covid-19 vaccine developed by China's Sinovac Biotech Ltd has shown an efficacy of 50.38 per cent in preventing symptomatic infections at a trial in Brazil, both Reuters and Bloomberg reported.

This means that the vaccine has barely passed the 50 per cent required for regulatory approval in Brazil, the BBC further highlighted.

It is currently one of two vaccines that Brazil is banking on for its national immunisation programme, with the other being the vaccine jointly developed by Oxford University and pharmaceutical firm AstroZeneca.

Previous announcement of 78 per cent efficacy comes under fire

As such, Butantan Institute, the medical centre conducting the trial, has come under fire for only releasing partial data in a previous announcement of the vaccine's efficacy rate.

On Jan. 7, Butantan had initially announced that the efficacy of the vaccine was 78 per cent for "mild-to-severe" cases.

However, it was not clear how Butantan had arrived at such a number and no mention was made of a group of "very mild" cases which had also received the vaccine.

The medical director for clinical research at Butantan, Richard Palacios, subsequently clarified on Jan. 12 that the new figure included data on these "very mild" infections.

Different efficacy rates emerge in Sinovac trials in other countries

In the meantime, different efficacy rates have been reported in the Sinovac vaccine's trials in other countries.

In Dec. 2020, a figure of 91.25 per cent was reported in Turkey while Indonesia reported an efficacy rate of 65.3 per cent.

In addition, only 1,620 people took part in the trial in Indonesia — a sample size too small for meaningful data, Bloomberg further highlighted.

Concern has since been raised that the vaccine trials of Sinovac are not subjected to the same level of scrutiny as Western-produced vaccines.

Indonesia has kicked off vaccination drive with Sinovac

Both Indonesia and Turkey have already ordered the Sinovac vaccine, with Indonesia's President Jokowi Widodo himself receiving a shot, to kick off the country's mass immunisation programme, Nikkei Asian Review reported.

Indonesia has also received 3 million doses of Sinovac which are ready for use and have distributed at least 1.2 million throughout the country as of Jan. 12.

The country aims to vaccinate 181 million people, out of the country's 270 million population, so as to achieve herd immunity.

Sinovac has also been ordered by Singapore

The Sinovac vaccine has also been ordered by Singapore.

Speaking in Parliament on Jan. 4, Health Minister Gan Kim Yong said that more vaccine deliveries from Moderna and Sinovac are expected in the coming months.

However both are still under review, and will have to meet stringent safety and efficacy requirements.

People will also not be able to choose which kind of vaccine they will receive, as this would "unnecessarily complicate" the "already-complex vaccination programme."

As per Gan:

"The allocation of vaccines will largely be based on medical indications of the different vaccines and the suitability of the vaccine for the different population subgroups, as well as availability of the vaccines."

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