NEW YORK, Dec 22 — Chinese vaccine maker Sinovac Biotech Ltd's Covid-19 vaccine has shown to be effective in late-stage trials in Brazil, the Wall Street Journal reported yesterday, 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 yesterday 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, the Journal reported.

The results from the Brazil trials put CoronaVac above the 50 per cent threshold that international scientists deem necessary to protect people, the Journal report said.

Butantan is poised tomorrow to announce CoronaVac's efficacy rate, according to the Journal.

Sinovac did not immediately respond to Reuters' request for comment.

Sinovac and AstraZeneca Plc's vaccine candidates may be ready for use in Brazil by mid-February, the country's health minister said last week. — Reuters