A Reuters tally showed new U.S. COVID-19 cases rose by nearly 50,000 on Wednesday, the biggest one-day spike on record, a day after the government's top infectious diseases expert warned that daily cases could double to 100,000 if the necessary steps were not taken. DEATHS AND INFECTIONS * For an interactive graphic tracking the global spread, open https://tmsnrt.rs/3aIRuz7 in an external browser. * For a U.S.-focused tracker with state-by-state and county map, open https://tmsnrt.rs/2w7hX9T in an external browser. * Eikon users, see MacroVitals (cpurl://apps.cp./cms/?navid=1592404098) for a case tracker and a summary of developments. AMERICAS * Governors of U.S. states hit hardest by the resurgent virus cases halted or reversed steps to reopen their economies, led by the nation's most populous state California. * Brazil's death toll crossed 60,000, with the governor of Sao Paulo state saying that a potential vaccine developed by China's Sinovac will be tested by 12 research centres in six Brazilian states. * Colombia's national COVID-19 tally surpassed 100,000 cases, while Mexico's death toll exceeded Spain's total number of fatalities from the virus. ASIA-PACIFIC * Australian police set up suburban checkpoints in hotspots in Melbourne and were considering using drones to enforce stay-at-home orders. * India's infections crossed 600,000 on Thursday, with 17,834 deaths. MIDDLE EAST AND AFRICA * Israel's parliament voted on Wednesday to allow the country's domestic intelligence agency to track cellphones of COVID-19 carriers for the next three weeks. * Nigeria will resume domestic flights from July 8. EUROPE * The British government will outline plans for air bridges later this week that will allow people to go on holiday to certain countries without facing quarantine on their return. * Spain and Portugal officially reopened their joint border to all travellers after a three-month closure. MEDICAL DEVELOPMENTS * A vaccine developed by German biotech firm BioNTech and U.S. pharmaceutical giant Pfizer has shown potential and was found to be well tolerated in early-stage human trials. * A leading scientist behind the University of Oxford's potential COVID-19 vaccine said the team has seen the right sort of immune response in trials but declined to give a firm time frame for when it could be ready. * Japan's Fujifilm announced a deal with India's Dr Reddy's and Dubai-based Global Response Aid to sell its anti-flu drug Avigan for COVID-19 treatment globally excluding Japan, China and Russia. ECONOMIC FALLOUT * Asian stocks tracked Wall Street higher although sentiment was cautious ahead of U.S. employment data, while copper prices jumped to more than six-month highs on a better global outlook and supply fears in top producer Chile. * St. Louis Federal Reserve president James Bullard told the Financial Times that a wave of "substantial bankruptcies" triggered by the pandemic could lead to a financial crisis. * Global tourism revenues are expected to fall by up to $3.3 trillion, with the United States standing to lose the most, according to a U.N. study.