The latest data from clinical trials in Brazil of a new coronavirus vaccine developed by China’s Kexing Biologicals show that it is only 50.4% effective, barely meeting the minimum threshold for internationally recognized vaccine effectiveness, and much lower than the data the company announced last week.
This new data is disappointing for Brazil. The Coxin vaccine is one of two vaccines chosen by the Brazilian federal government to respond to the second wave of the outbreak. The other is the Oxford/AstraZeneca vaccine.
Brazil has one of the worst outbreaks in the world, with more than 8 million examples of infections and more than 200,000 deaths so far.
The effectiveness rate announced by Coxin last week was 78%, which is significantly lower than the 90%+ effectiveness rate of the U.S.-U.K. vaccine, but is still reasonable. But the new figure is actually nearly 30 percentage points lower than 78%, which has negative implications for the credibility of Kexing, and even Chinese vaccines.
Some scientists and observers have complained that the repeated delays in releasing the data by the Brazilian Butantan Institute have led to excessively high expectations for the new data and caused confusion in Brazil.
The repeated delays in data from the Coxin vaccine trials in Brazil are allegedly related to deaths during the tests. Brazilian authorities are hesitant to approve emergency use of the Coxin vaccine. There are reports that Brazilian health regulators plan to meet this weekend to discuss the matter.
Chinese official media Global Times immediately responded to the new data released by Brazil. The newspaper said that while the overall protective efficacy of the Coxin vaccine was only 50.4 percent, it was tested in Brazil mainly on high-risk health care workers and patients with moderate and severe illnesses, for which the efficacy was 100 percent. When mildly ill patients are added, the efficacy of protection is 77.96%.
Phase III clinical trials of the Coxin vaccine were conducted in three countries: Brazil, Indonesia and Turkey. Previously, the clinical results published in Turkey showed a vaccine efficacy of 91.3%, and the clinical results in Indonesia showed a vaccine efficacy of 65.3%.
The clinical efficacy of the vaccines developed by Pfizer/German Biotech and Modena reached 95 and 94.1%, respectively, and the efficacy of the Oxford/AstraZeneca vaccine was 70.4%.
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