In the latest global COVID-19 developments, the United Kingdom today announced the launch of the first study to explore giving different COVID-19 vaccines in a two-dose regimen, and a new study added more evidence that the B117 variant is deadlier than the standard version of the virus.A more agile approach for limited vaccine supply?The trial of a mixed-vaccine strategy comes as governments look for ways to protect as many people as possible as quickly as possible with vaccines, amid short supply and the threat of more contagious and lethal coronavirus variants.In a statement, the UK government said it has provided $9.6 million to back a study that will look at the effects of mixing vaccine types for the two doses, such as the one from