The number of coronavirus infections around the world passed 15 million on Wednesday with more than a quarter of those cases in the United States, where President Donald Trump warned that the pandemic was likely to get worse before it gets better.

The US data makes grim reading with more than 140,000 fatalities and regular daily death tolls of more than 1,000, yet Trump repeated his claim late on Tuesday that the pandemic would somehow "disappear".

Trump has been a critic of lockdown measures and has argued in favour of reopening the economy even as death tolls have climbed.

Signs are emerging in other parts of the world that the virus quickly springs back when lockdown measures are lifted.

Australia, Belgium, Hong Kong and Japanese capital Tokyo had all used restrictive measures to successfully beat outbreaks earlier in the pandemic, but all are now facing an upsurge in cases.

Australia and Hong Kong set new daily records for confirmed cases on Wednesday and Tokyo's governor urged residents to stay at home during a forthcoming holiday as cases climb. 

Belgian officials said people must stick to social-distancing guidelines to halt a "snowball effect before it provokes a new avalanche".

However, one of the more controversial measures taken by any government -- South Africa's decision to ban the sale of alcohol and enforce a curfew -- continued to cause anguish.

"What the government has put in place has been knee-capping," restaurateur Sean Barber said during a protest in Johannesburg. "It's decimating our industry."

- Vaccine hopes -

The crisis has left tens of millions unemployed around the world and crippled global commerce, prompting the European Union to agree an unprecedented 750 billion euro ($858 billion) aid package for the hardest-hit member countries earlier this week.

But the airline industry continues to struggle under the weight of travel restrictions and reluctance among potential passengers to fly.

Irish carrier Ryanair said on Wednesday it would shut its base near the German business hub Frankfurt after pilots refused to take a pay cut.

The firm, which is looking to shed 3,000 staff in total, said the pilot's union had "voted for job cuts and base closures when they could have preserved all jobs".

The production of a vaccine is now key to ensuring a return to something close to normality for businesses and the general public. 

More than 200 candidate drugs are being developed with 23 having progressed to clinical trials.

The US government has agreed to pay almost $2 billion for 100 million doses of a potential vaccine being developed by German firm BioNTech and US giant Pfizer.

Another leading candidate, developed in part by pharmaceutical giant AstraZeneca, registered promising results from clinical trials this week. 

But the firm's chief said on Tuesday a global rollout was not imminent.

"We hope to be able to produce a vaccine by the end of the year... perhaps a little earlier if all goes well," said Pascal Soriot.

- 'Bake a giant cake' -

With the sporting world just about getting back on its feet, Olympic officials conceded on Wednesday that their hopes of holding the Tokyo 2020 Games next year rested on a vaccine.

"If things continue as they are now, we couldn't" hold the Games, said local organising committee president Yoshiro Mori.

While global efforts to prevent new infections are the principal concern of policymakers, the extent and severity of the disease in countries with struggling health systems has becoming clearer in recent days.

India passed the one-million infections milestone last week and is now behind only the US and Brazil, but new data on Wednesday suggested a vast underestimate.

A study showed almost a quarter of the population in New Delhi had contracted the virus, equating to roughly five million infections in the capital city.

Officials have registered just 125,000 cases.

Meanwhile, for those who recover from the disease, the path back to full health is not always straightforward.

In Brazil, 63-year-old Elenice da Silva had a severe infection that lasted nearly three months.

The illness left her temporarily unable to speak.

"Intensive care was awful. But now I'm feeling marvellous," she told AFP during her recovery. "I'm going to bake a giant cake for everyone."