Study Seems To Show Chinese COVID-19 Vaccine Only 50% Effective, Prompting Clarification From China

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Dylan Housman Deputy News Editor
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Brazil’s Butantan Institute released numbers calling into question the efficacy of China’s CoronaVac vaccine Wednesday, prompting China to respond in order to clarify the numbers. 

Butantan is in final-stage trials for CoronaVac, a COVID-19 vaccine manufactured by China’s SinoVac, and submitted results to Brazilian regulators Tuesday declaring an efficacy rate of just over 50%, according to the South China Morning Post. A week prior, Butantan, a partner of SinoVac, submitted results indicating CoronaVac was 78% effective in preventing mild cases of COVID-19 and 100% effective in preventing severe cases, according to SCMP. 

SinoVac chairman Yin Weidong clarified Wednesday that the Brazilian trials had found the CoronaVac 100% effective against severe cases, 78% effective against cases “requiring treatment,” and 50% effective in “protecting medical workers.” Studies in Turkey and Indonesia yielded more varying numbers, though, showing efficacy rates of 91% and 65%, respectively, the SCMP reports

Yin said that 500 million doses of the vaccine were already being produced, with doses being distributed both in China and internationally. “However, these facilities are still far short of the orders we have received from many countries, including Indonesia, Malaysia, Singapore and the Philippines,” he added. (RELATED: Brazilian President Who Recovered From COVID-19 Says He Won’t Get Vaccine)

By comparison, Astrazeneca, Pfizer, and Moderna’s vaccines are all more than 90% effective.