Sinovac vaccine effective against virus variants in Brazil; efficacy rises if injection interval is more than 21 days Hu Yuwei Published: Apr 12, 2021 10:43 PM Guarani indigenous chief Jurema Nunes, receives a CoronaVac vaccination shot during a COVID-19 vaccination campaign in Marica, Brazil, on January 20. Photo: VCG China's Sinovac COVID-19 vaccine has 50.7 percent efficacy and has proved to be effective against the variants known as P1 and P2 that are prevalent in Brazil, latest data showed. Moreover, the Sinovac vaccine's efficacy rate can climb to 62.3 percent with an interval of more than 21 days between doses rather than 14 days. The findings appear in the latest report released on Sunday by Sao Paulo's state-owned Butantan Institute, which tested and produced Sinovac's COVID-19 inactivated vaccine named CoronaVac.