Sinovac Covid Shot More Than 50% Effective, But Data Withheld
- Brazil trial findings delayed at request of China’s Sinovac
- Lack of more detail may dent faith in Chinese vaccines
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A Covid-19 vaccine developed by Chinese pharmaceutical firm Sinovac Biotech Ltd. was found to be more than 50% effective in a Brazilian clinical trial, though researchers delayed releasing more information at the request of the company.
A 50% efficacy rate is a minimum standard set by U.S. regulators for emergency authorization of Covid vaccines. Messenger RNA vaccines from Moderna Inc. and Pfizer Inc. have produced far better results, reducing symptomatic Covid cases by well over 90% in giant trials.