Chinese vaccine maker Sinovac Biotech's Covid-19 vaccine proved effective in late-stage trials in Brazil, <em>The</em> <em>Wall Street Journal</em> reported on Monday, citing people involved in the vaccine's development. Sao Paulo state's Butantan Institute, which is organising the late-stage trials of Sinovac's vaccine CoronaVac in Brazil, said on Monday that any reports on the efficacy of the shot before a Wednesday announcement were "mere speculation". Brazil is the first country to complete late-stage trials of CoronaVac, which is also being tested in Indonesia and Turkey, <em>The WSJ</em> reported. The results from the Brazil trials put CoronaVac above the 50 per cent threshold that international scientists consider necessary to protect people, the report said. The Butantan Institute is expected on Wednesday to announce CoronaVac's efficacy rate,. Sinovac and AstraZeneca's vaccine candidates may be ready for use in Brazil by mid-February, the country's health minister said last week.