FACTBOX-Latest on the worldwide spread of the coronavirus

* A major Taiwanese Buddhist group said it had signed a deal to buy 5 million doses of BioNTech SE's vaccine via the German firm's Chinese sales agent, bumping the island's order for the shot up to 15 million doses. AMERICAS * The Delta variant is the cause of more than 80% of new U.S. cases, but the authorised vaccines remain more than 90% effective in preventing hospitalisations and deaths, said top U.S. infectious disease expert Anthony Fauci in a Senate hearing. * A fully vaccinated White House official tested positive off site, White House press secretary Jen Psaki said.

Britain's COVID-19 cases rose by nearly 41% over the past week, while the chief of the Tokyo 2020 organising committee did not rule out cancelling the Olympics if infections spiked, as more athletes tested positive and sponsors ditched plans to attend Friday's opening ceremony. 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

* The Delta variant is now the majority variant of the virus circulating in France, French Prime Minister Jean Castex said. * London's High Court ruled that Britain acted lawfully over its so-called traffic lights system for travellers entering Britain in a case brought by Manchester Airports Group, backed by a number of airlines.

* Arsenal have cancelled their pre-season tour to the United States after a small number of positive cases at the club, the team said. ASIA-PACIFIC

* Japanese health experts said there were concerns that rising cases in Tokyo could add to the burden on the medical system and create delays in patient care. * Australia's two largest states reported sharp increases in new cases, a blow to hopes that lockdown restrictions would be lifted with more than half the country's population under stay-at-home orders.

* The first test batch of Russian-developed Sputnik V vaccine has been produced in Vietnam, Russia's sovereign wealth fund RDIF and Vietnamese pharmaceutical firm VABIOTECH said. * A major Taiwanese Buddhist group said it had signed a deal to buy 5 million doses of BioNTech SE's vaccine via the German firm's Chinese sales agent, bumping the island's order for the shot up to 15 million doses.

AMERICAS * The Delta variant is the cause of more than 80% of new U.S. cases, but the authorised vaccines remain more than 90% effective in preventing hospitalisations and deaths, said top U.S. infectious disease expert Anthony Fauci in a Senate hearing.

* A fully vaccinated White House official tested positive off site, White House press secretary Jen Psaki said. Psaki also said she is in regular contact with the conservative news network Fox News about its coverage of the vaccine. MIDDLE EAST AND AFRICA

* Pfizer and BioNTech said they had struck a deal for South Africa's Biovac Institute to process and distribute over 100 million doses a year of their COVID-19 vaccine for the African Union beginning in 2022. * Iran imposed a one-week lockdown in the capital and a nearby province as daily caseloads hit a record high, state television reported.

MEDICAL DEVELOPMENTS * Sinopharm's vaccine elicited weaker antibody responses against the Delta variant, based on the first published study of its effect against the more contagious version.

* Europe's drug regulator said it had started a real-time review of the vaccine developed by French drugmaker Sanofi and Britain's GlaxoSmithKline, the fifth shot currently under such a review. ECONOMIC IMPACT

* European stocks lifted and bond prices fell across the euro area on Wednesday as investors bet an earlier flight to safety sparked by fears about the spread of the Delta variant was overdone. * Japan brought forward the expected timing for achieving a primary balance surplus by two years to fiscal 2027 due to a surprise rise in tax revenues, even as the pandemic hobbled a fragile economic recovery.

(Compiled by Federico Maccioni, Vinay Dwivedi and Devika Syamnath; Edited by Shounak Dasgupta, Arun Koyyur, William Maclean)