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Chinese Covid-19 vaccine reported as just over 50% effective, down from 78%

Maya Taylor



PHOTO: Andressa Anholete/Getty Images

Confusion reigns over the exact efficacy rate of a Chinese Covid-19 vaccine due to be rolled out in Thailand next month. Thailand has ordered 2 million doses of the Sinovac Biotech vaccine, while its rollout among high-risk groups in Indonesia is expected to begin this week. However, questions now hang over the vaccine’s efficacy rate, originally reported as 78% in trials in Brazil but more recently downgraded to just over 50%. In total, 4 different efficacy rates have been reported, depending on the country conducting trials.

In Indonesia, where President Joko Widodo is set to get his first dose of the jab today, data from a local trial indicates an efficacy rate of 65%. However, with only 1,620 participants, the trial is considered too small for the data to have much value. Last month, Turkey reported an efficacy rate of 91.25% in its trial, which was also deemed too small to provide meaningful statistics.

The largest trial of the Chinese vaccine has been in Brazil, with 13,000 participants. There, however, 2 quite different efficacy rates have been reported. Just last week, the Butantan Institute, which partnered with Sinovac for the trials, reported that the vaccine was 78% effective in preventing mild cases of the virus and 100% effective in stopping severe and moderate infections.

However, the institute was forced to revise those figures yesterday, confirming instead an overall efficacy rate of 50.38%. The decreased rate comes after researchers came under pressure for a lack of transparency in reporting trial data. Ricardo Palacios from Butantan says the revised figure includes cases categorised as “very mild”, as no medical treatment was required.

It’s understood the Butantan Institute delayed announcing its results 3 times, which they say was due to a confidentiality clause in the contract with Sinovac. The disparity in reporting has raised some questions about the Chinese vaccine, with concerns that it is not receiving the same level of scrutiny as those produced in Europe or the US.

However, it’s not the first time there has been confusion over efficacy rates, with AstraZeneca initially reporting 2 different rates depending on the dosage administered. The Chinese vaccine still meets the efficacy threshold required for regulatory approval, at over 50%.

SOURCE: GMA News | Bloomberg


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  1. Avatar


    Wednesday, January 13, 2021 at 10:54 am

    “lack of transparency in reporting trial data.“ of a Chinese vaccine, that was a given before the trial even started. Wait so the efficacy threshold required for Thailand is only 51%? Ok I guess ….

  2. Avatar

    Dirk Hunter

    Wednesday, January 13, 2021 at 11:10 am

    Thailand bought 2 million doses from Chinese company and now other countries reporting that same vaccine only 51 percent effective?

    Thailand government would have had better luck ordering online with Shopee, Lazada or Ali-Express.

  3. Avatar


    Wednesday, January 13, 2021 at 11:25 am

    So there’s nothing wrong with the vaccine then. Glad we sorted that out in the end.

  4. Avatar

    Issan John

    Wednesday, January 13, 2021 at 1:03 pm

    Oops … rather worrying not only for Thailand but for the UAE (who reported 86% effectiveness in their trial), Bahrain, Brazil, Chile, Indonesia, Malaysia, Laos, Vietnam, Cambodia and Turkey, plus a few others.

    … could be why China bought 100 million doses from AstraZeneca, though …

  5. Avatar

    James Pate

    Wednesday, January 13, 2021 at 1:09 pm

    Singaporeans are getting the Pfizer vaccine. ?? Wish I was, too.?

  6. Avatar


    Wednesday, January 13, 2021 at 6:45 pm

    Seeing as I would hate to deprive a Thai person from the “opportunity” of getting the vaccine – I will happily wait….

    They can keep the monkey virus particles, the sterilization additives, the mercury and the vaccine adjuvants.

  7. Avatar


    Thursday, January 14, 2021 at 12:43 am

    Wonder which vaccine Xi is getting? Not the one Thailand bought.

    I’d rather wait for something a little more effective.

  8. Avatar


    Thursday, January 14, 2021 at 1:04 pm

    medical chiefs in china declare is was 79% proof,they didnt mention that was for the mildest symptom of this virus,with 50.7% proof for the worst very reassuring if the government were first to use this vaccine ?

  9. Avatar


    Thursday, January 14, 2021 at 3:28 pm

    everybody is so laser focused on the miracle vaccines but those will not solve the massive damage already done and what’s still coming. It will take at least till may when the masses will get vaccinated widespread everywhere and till then most hard lockdowns already in place will stay in place most likely to the end of this year listening to many politicians… what really will f*ck shit up Are all the reports that there are increases in suicides up from 1 to a staggering 145%! Massive increases in domestic abuse, self medication and all the other downsides of the measures in place. There are tens of thousands of mentally sick people that where already walking on the edge before covid and not getting help now and we’re talking about sex offenders, muderers and the rest of them that ain’t getting the needed treatment and that’s in the Netherlands alone that number. On top of that all the businesses closing and most not surviving or coming back, and you can go on and on about all the different problems and issues this has caused and anybody that even thinks for a second that this will just all go away with these miracle vaccines is a moron, everyone knows it will get a lot, and I mean ALOT worse upcoming year at minimum before there will be any improvements noticibly.

  10. Avatar


    Thursday, January 14, 2021 at 7:45 pm

    Is this vaccine made in the same Wuhan laboratory as….?

  11. Avatar


    Thursday, January 14, 2021 at 10:40 pm

    The Chinese are making their vaccines the old fashioned way, the same way the west was previously making their flu shots which were also 51% effective, now astro zeneca etc are using a different technology which is a lot more effective, I don’t remember the name.

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