In contrast, there appeared to be some movement forward in the sprint to find a vaccine against COVID-19, bolstered by a $US1 billion ($A1.5 billion) investment from the US government's vaccine agency.

British Prime Minister Boris Johnson pledged to have a "test, track and trace" program for COVID-19 in place by June 1 as part of a strategy to persuade the country that it's safe to move on to the next stage of easing the lockdown and restarting the economy.

But the government also appeared to backtrack on an earlier pledge to make a smart phone app a pillar of that program.

Security minister James Brokenshire told the BBC on Thursday that he remains "confident" that the tracing system will be in place by June 1, but acknowledged that an app intended to help track the virus was not ready. He suggested "technical issues" were the reason for its failure to be introduced as planned by mid-May.

Experts say that being able to quickly identify people exposed to the virus can help stop the spread of the contagious respiratory illness but efforts to put apps in place have come up across technical problems and fears of privacy intrusions.

The French government has also been forced to delay deployment of its planned contact-tracing app. Initially expected last week as the country started lifting confinement measures, it won't be ready before next month due to technical issues and concerns over privacy.

Italian Prime Minster Giuseppe Conte said on Thursday that the country's contact-tracing app would begin tests "in the coming days".But he made no mention of whether Italy had hired teams of contact-tracers to actually conduct interviews and get in touch with people who had been in contact with COVID-19 patients, as other European countries have done.

Spain's Economy Minister Nadia Calvino said on Wednesday in parliament that Spain is making preparations to test a European Bluetooth-based app at the end of June in the Canary Islands.

But the adoption of the app has taken a back seat to the hiring of old-school human tracers in Spain. The government has said that the technology will be adopted only if it adds value to the tracing efforts that are being deployed by the country's 17 regional administrations.

Meanwhile, drug maker AstraZeneca said on Thursday it has secured the first agreements for 400 million doses of a COVID-19 vaccine that is now being tested at the University of Oxford, one of the most advanced projects in the search for a vaccine.

The Anglo-Swedish company reported it had received more than $US1 billion from the US Biomedical Advanced Research and Development Authority for the development, production and delivery of the vaccine, starting in the northern autumn.

AstraZeneca CEO Pascal Soriot said the company "will do everything in our power to make this vaccine quickly and widely available".

In China, the country's communist leadership was taking extensive precautions to prevent any infections as it opens its National People's Congress on Friday and a parallel meeting of advisers on Thursday. The meetings in Beijing were delayed for nearly two months due to the pandemic.

An outbreak at the congress would be a potential public relations nightmare as President Xi Jinping showcases the country's apparent success in curbing the coronavirus that was first detected in the central city of Wuhan late last year.

About 5 million people worldwide have been confirmed infected and more than 328,000 deaths have been recorded, according to a tally kept by Johns Hopkins University.

Australian Associated Press