British government says 300 healthy people will be immunized with 2 doses of experimental shot developed at Imperial College London, which has been backed by official funding

No details published, but Health Ministry source says no action now would mean waiting a year or more once vaccine is available

Report comes as countries scramble to ensure they will be among first to receive vaccines, if and when they become available; US biotech company to begin Phase 3 trials next month

US biotech firm's shares soar as it claims progress in trials; analysts says sales, including by Israeli chief medical officer, are legal but undermine faith in company's future

US biotech firm's shares soar as it claims tests of first volunteers show its vaccine candidate produces immune response, 'has potential to prevent COVID-19'; Phase 3 tests in July