by BY JOHN BOWDEN — thehill.com — Health officials in Brazil said Tuesday that a Chinese-produced vaccine for COVID-19 is just over 50 percent effective in preventing infections, above the World Health Organization’s (WHO) benchmark standards for vaccine effectiveness but far below several vaccines produced by Western nations. The New York Times reported that the Butantan Institute in São Paulo released findings indicating that the CoronaVac injection produced by Sinovac was far less effective than competing candidates produced by companies Moderna, Pfizer and AstraZeneca. The actual effectiveness rate is also far lower than the rate officials previously estimated the Sinovac candidate to have; it was reported last week that officials in São Paolo had estimated the CoronaVac to be 78 percent effective at preventing COVID-19.

The difference appears to be in terms of data collection, as the figures released last week did not count patients who experienced “very mild” coronavirus infections after receiving the shot. Overall, the CoronaVac remains 100 percent effective at preventing “severe” or “moderate” coronavirus infections, the Butantan Institute has found, while mild or very mild infections remain possible after receiving the shot.