Volunteers rolled up their sleeves Monday to take part in the biggest test yet of an experimental COVID-19 vaccine. The first of some 30,000 volunteers were receiving shots created by the U.S. government as part of the all-out global race to stop the outbreak. It will be months before results trickle in. Meanwhile, President Donald Trump’s national security adviser tested positive for the virus. And there were setbacks in efforts to restart American baseball, with two major league games canceled because of a outbreak, and for Europe’s plans to restart tourism, with rising infection rates in Spain causing concern for that country’s neighbors.