The CoronaVac Covid-19 vaccine developed by China’s Sinovac Biotech Ltd showed efficacy between 50 per cent and 90pc in Brazilian trials, Sao Paulo’s state health secretary has said, and its Brazilian producer said full trial results will be released by Jan 7.

Results of trials in Brazil are known exclusively by Sao Paulo state’s Butantan Institute biomedical research centre, which has an agreement with Sinovac to produce the vaccine, said health secretary Jean Gorinchteyn.

First trials showed efficacy above 50pc, the minimum required by Brazilian health regulator Anvisa, and below 90pc, Gorinchteyn said in an interview with CBN radio.