FACTBOX-Latest on the worldwide spread of the coronavirus

* The European Union has exercised an option to acquire an additional 100 million doses of BioNTech and Pfizer's COVID-19 vaccine, the two companies said. AMERICAS * New U.S. cases fell 0.4% last week after rising for four weeks in a row, according to a Reuters analysis of state and county data. * Production of JNJ's vaccine at a U.S. manufacturing plant was halted by the U.S. Food and Drug Administration, while the agency investigates an error that led to millions of doses being ruined last month.

India will let all citizens over 18 have COVID-19 vaccinations from May 1, as the health system creaked under the weight of record-high cases and the capital region of New Delhi ordered a lockdown. 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

* Russian scientists have found the Sputnik V vaccine 97.6% effective against COVID-19 in a "real-world" assessment based on data from 3.8 million people, Moscow's Gamaleya Institute and the Russian Direct Investment Fund said. * Greece has suspended a planned rollout of Johnson & Johnson's (JNJ) COVID-19 vaccinations but does not expect that to impact its overall inoculation programme.

* Britain will add India to its travel "red-list" on Friday after detecting 103 cases of a coronavirus variant first identified in the country. * The European Union has exercised an option to acquire an additional 100 million doses of BioNTech and Pfizer's COVID-19 vaccine, the two companies said.

AMERICAS * New U.S. cases fell 0.4% last week after rising for four weeks in a row, according to a Reuters analysis of state and county data.

* Production of JNJ's vaccine at a U.S. manufacturing plant was halted by the U.S. Food and Drug Administration, while the agency investigates an error that led to millions of doses being ruined last month. * The world can bring the pandemic under control in the coming months provided it distributes the necessary resources fairly, the head of the World Health Organization told a news briefing.

ASIA-PACIFIC * India will waive its 10% customs duty on imported COVID-19 vaccines, a senior government official told Reuters. The government will also fund a production capacity boost for vaccine makers Serum Institute of India and Bharat Biotech.

* A recent surge in cases could see major parts of Japan slide back into states of emergency, while quarantine-free travel started between Australia and New Zealand for the first time in more than a year. MIDDLE EAST AND AFRICA

* Israel signed a deal to buy millions of doses of vaccine from Pfizer through 2022. * The South African government's compensation fund to cover potential injuries from COVID-19 vaccines could cost around 250 million rand ($17.5 million) in the first year.

MEDICAL DEVELOPMENTS * The United States is reviewing reports of a handful of potential cases of severe side effects among people who received JNJ's vaccine in addition to those that led to a pause in its use.

* Spain will study the effects of mixing different coronavirus vaccines, government researchers said. ECONOMIC IMPACT

* An index of stocks across the world dipped, on track to end Monday with the largest daily drop in almost four weeks, after touching a record high and investors looking for earnings to justify the high valuations. * Canadian Prime Minister Justin Trudeau's government lined up billions in new spending to provide emergency support during a virulent third wave of COVID-19.

(Compiled by Devika Syamnath and Anita Kobylinska; Editing by Kirsten Donovan and Arun Koyyur)