FACTBOX-Latest on worldwide spread of the coronavirus

Britain began its third COVID-19 lockdown on Tuesday with the government calling for one last major national effort to defeat the spread of a virus that has infected an estimated one in 50 citizens before mass vaccinations turn the tide.

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 * More than 1.3 million people in the United Kingdom have been vaccinated against COVID-19 and Prime Minister Boris Johnson pledged to publish daily statistics on who is receiving shots in an effort to end England's new lockdown.

* Five UK medical scientists have criticised a British government plan to delay giving second doses of COVID-19 vaccines by up to 12 weeks, saying proven dosing schedules should not be altered "without solid scientific support or evidence". * Travellers arriving in Germany from risk regions will have to test for the coronavirus twice, Chancellor Angela Merkel said after announcing an extension of an existing lockdown as well as some tougher measures.

* Boris Johnson said his government would soon demand COVID-19 tests for passengers arriving from overseas. * France reported 20,489 new confirmed coronavirus infections on Tuesday, nearly double the 11,395 reported last week Tuesday and more than five times the 4,022 reported on Monday, which usually sees a drop in numbers due to weekend reporting lags.

* France is stepping up its COVID-19 vaccine rollout by widening the first target group to include more health workers and simplifying a cumbersome process to deliver shots more quickly. * Denmark imposed new lockdown measures aimed at curbing the rapid spread of a new coronavirus variant that is believed to be more transmissible.

AMERICAS * More than two-thirds of the 15 million coronavirus vaccines shipped within the United States have so far gone unused, as the governors of New York and Florida vowed to penalise hospitals that fail to dispense shots quickly enough.

ASIA-PACIFIC * Indian health authorities are ready to roll out a COVID-19 vaccination programme by next week, the country's top health official said.

* Vietnam suspended inbound flights from countries with new COVID-19 variants, initially Britain and South Africa, the health ministry said. MIDDLE EAST AND AFRICA

* Iran and Oman have registered their first two cases of a highly contagious coronavirus variant that emerged in Britain. MEDICAL DEVELOPMENTS

* COVID-19 patients should take two doses of the Pfizer and BioNTech vaccine within a period of 21-28 days, the World Health Organization said on Tuesday as many countries grappled with a more highly infectious coronavirus variant. * There is no indication that the coronavirus variant identified in South Africa is more transmissible than the one spreading fast in Britain, the World Health Organization's technical chief on COVID-19, Maria Van Kerkhove, said.

ECONOMIC IMPACT * U.S. factory activity accelerated to its highest level in nearly 2-1/2 years in December as the pandemic continues to pull demand away from services towards goods.

* The global economy is starting 2021 in a better position than had been expected in 2020, but surging COVID-19 cases and new strains of the virus are clouding the outlook and making for a "dark winter," the International Monetary Fund's chief economist said on Tuesday. * Global equity indexes were mostly higher on Tuesday after Wall Street started the year with losses on Monday, while the U.S. dollar weakened.

(Compiled by Amy Caren Daniel; Edited by Shounak Dasgupta)