Washington has confirmed it is working on a plan to lend 1.5 million doses of the Oxford-AstraZeneca COVID-19 vaccine to Canada, while the military commander in charge of the rollout here says all adults who wish could be able to get their first shot by July 1. White House press secretary Jen Psaki said Thursday that details have not been fully worked out and that another 2.5 million doses would go to Mexico. The United States currently has seven million “releasable” doses of the vaccine, which has yet to receive approval from its Food and Drug Administration, she said. “Balancing the need to let the approval process play out … with the importance of helping stop the spread in other countries, we are assessing how we can loan doses,” Psaki told a media briefing. The loan would be in lieu of a future exchange of doses from Canada and Mexico, …