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 on Monday, citing people involved in the vaccine’s development.

Sao Paulo state’s Butantan Institute, which is organizing 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, the Journal reported here.

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

Butantan is poised on Wednesday 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.

Reporting by Manojna Maddipatla in Bengaluru; Editing by Maju Samuel and Peter Cooney / REUTERS