FACTBOX-Latest on the worldwide spread of the coronavirus

Britain became the first country to give the go-ahead for human challenge trials in which volunteers will be deliberately exposed to COVID-19.

DEATHS AND INFECTIONS * Eikon users, see COVID-19: MacroVitals https://apac1.apps.cp.thomsonreuters.com/cms/?navid=1592404098 for a case tracker and summary of news.

EUROPE * Pfizer has yet to deliver about 10 million COVID-19 vaccine doses to the European Union that were due in December, leaving it about one-third short of the supplies it had expected by now.

* Prime Minister Boris Johnson is plotting a staged exit from lockdown that would see the United Kingdom's battered economy returning to work over the next five months. * Switzerland plans its first "cautious steps" to reopen the country next month, as spending to tackle the pandemic pushed the country to its largest-ever budget deficit.

* The Dutch government raced to prepare legislation to keep a nighttime curfew in place after a court ordered it to scrap the controversial measure. * Croatia is discussing with Moscow the possibility of importing Russia's vaccine, and the government has asked the drugs regulator to consider approving the shot without waiting for the European Union.

AMERICAS * Head nurse Veronica Luz Machado, who for months has battled the pandemic from an intensive care unit in the northern Colombian city of Sincelejo, became the first person in the Andean country to receive a COVID-19 vaccine.

* The White House is increasing the supply of vaccines sent each week to states to 13.5 million doses, and is also doubling the amount shipped to pharmacies to 2 million doses this week. ASIA-PACIFIC

* Nearly 4,000 Indonesian firms, many of them textile companies, have signed up to take part in a proposed scheme that would allow the private sector to buy vaccines procured by the government and inoculate their staff. * India will increase the number of its vaccination sites by up to five times after administering nearly 9 million shots in a month.

* Japan launched its inoculation drive on Wednesday. MIDDLE EAST AND AFRICA

* South Africa launched its vaccination drive, battling to tame a more infectious variant of the coronavirus with a rollout of the Johnson & Johnson shot. * Gaza received its first shipment of vaccines on Wednesday after Israel approved the transfer through its border with the Hamas Islamist-run territory.

* Zimbabwe will begin vaccinating on Thursday, starting with health workers and other essential service personnel. MEDICAL DEVELOPMENTS

* European Union said the production capacity of a factory in Belgium that produced shots for AstraZeneca had "drastically" increased, while the European Commission said it had struck a deal for an extra 150 million doses of Moderna's vaccine this year, nearly doubling the number of shots secured for 2021. * Biotechnology group Biophytis said it had got regulatory approval in France and Belgium to recruit more patients for a study of Sarconeos as a potential treatment for breathing problems associated with COVID-19.

* Nigerian students have built a machine they hope can one day help hospitals remotely treat COVID-19 patients, taking temperatures, transporting medicine and allowing medical workers to communicate with patients with a webcam and screen. ECONOMIC IMPACT

* The rally in stock markets stalled on Wednesday as a surge in U.S. Treasury yields on optimism about a swift economic recovery put pressure on company valuations. * Germans' nominal earnings fell for the first time in over a decade, the statistics office said, releasing data that showed the pandemic having a more severe impact on earnings than the 2007/08 financial crisis.

(Compiled by Anita Kobylinska and Veronica Snoj; editing by Larry King and Nick Macfie)