Researchers revealed during revised testing of Chinese company Sinovac’s COVID-19 shot that it was almost 30% less effective than previously thought. Originally, Brazil’s Butantan Institute, a research center based in Sao Paulo, tested the CoronaVac drug in phase 3 trials and announced it was 78% effective in protecting against COVID-19.
Pressure from scientists around the globe who questioned the results prompted the Butantan researchers to recalibrate their data, which did not originally include volunteers with very mild cases of COVID-19 who did not require medical assistance. When this tier of participants was added to the study results, the efficacy rate of CoronaVac plummeted to 50.38%, Butantan announced Tuesday, according to The Wall Street Journal.
According to the Centers for Disease Control and Prevention, in phase 3 trials, the vaccine is given to thousands of people to guarantee efficacy and safety. According to The Washington Post, Chinese and Russian firms are projected to be among global vaccine production leaders in 2021.
Naor Bar-Zeev, an expert on international health and disease epidemiology at the Johns Hopkins Bloomberg School of Public Health, said there is no reason to doubt the development of effective vaccines from these world leaders but adds that the bottom line is the result of properly conducted phase 3 trials.
Many public health experts defend the use of the Chinese vaccine, saying that it still offers more protection than the average flu shot and is easily stored in a regular refrigerator. However, the inaccuracy of the phase 3 clinical trial data has made Brazilians reluctant to take the vaccine, said the Journal.
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