Brazilian President Jair Bolsonaro has overruled his own health minister, rejecting the announced purchase of 46 million doses of CoronaVac, a potential vaccine against Covid-19 being tested in Sao Paulo state.

A state-owned Chinese company is setting up production lines to supply one billion doses of two possible coronavirus vaccines that are being tested on 50,000 people in 10 countries, its chairman has announced.

A Chinese pharmaceutical company has said the coronavirus vaccine it is developing should be ready by early 2021 for distribution worldwide.

Johnson & Johnson is beginning a huge final study to try to prove if a single-dose Covid-19 vaccine can protect against the disease.

Openly contradicting the government’s top health experts, President Donald Trump has predicted that a safe and effective vaccine against the coronavirus could be ready as early as next month and in mass distribution soon after.

The announcement on Tuesday by Russian president Vladimir Putin that his country was the first to approve a coronavirus vaccine has been met by doubts about the science and safety.

Russian President Vladimir Putin says a coronavirus vaccine developed in the country has been registered for use and one of his daughters has already been inoculated.

The biggest test yet of an experimental Covid-19 vaccine got underway in the US on Monday with the first of some 30,000 Americans rolling up their sleeves to take part.