The Trump administration this week announced the closing of a $1.5 billion contract under which the federal government will purchase 100 million doses of an eventual COVID-19 vaccine produced by the biotechnology company Moderna, the sixth such deal reached since May. “I’m pleased to announce that we have reached an agreement with Moderna to manufacture and deliver 100 million doses of their coronavirus vaccine candidate,” the president sait at a White House news conference. “The federal government will own these vaccine doses, we’re buying them.” In a statement, Moderna Chief Executive Stéphane Bancel welcomed the deal. “We appreciate the confidence...