WASHINGTON (Reuters) - The United States plans to send roughly 4 million doses of AstraZeneca’s COVID-19 vaccine that it is not using to Mexico and Canada in loan deals with the two countries, bowing to pressure to share vaccine with its allies. Mexico will receive 2.5 million doses of the vaccine and Canada is to receive 1.5 million doses, White House spokeswoman Jen Psaki said. “It is not fully finalized yet but it is our aim,” she told a daily briefing. The Biden administration has come under pressure from countries around the world to share vaccines, particularly its stock of AstraZeneca, which is authorized for use elsewhere but not yet in the United States. AstraZeneca has millions of doses made in a U.S. facility, and has said that it would have 30 million shots ready at the beginning of April. The company’s shares rose slightly after Reuters first reported the news. The deal to share the vaccine does not affect President Joe Biden’s plans to have vaccine available for all adults in the United States by the end of May, a senior administration official said, and it does not reduce the supply of available vaccine in the United States. Two officials said the vaccine would be delivered in “short order” once the deal was completed, but they declined to give a more specific timetable. The so-called “releasable” vaccines should be ready for use once they arrive in Mexico and Canada. Under the deal, the United States will share doses with the two countries now with the understanding that they will pay the United States back with doses in return. The official said that would take place later this year. Psaki said the United States had access to 7 million releasable doses of the AstraZeneca vaccine but had no plans to share the vaccine with other countries at this time. “We ... have a number of requests from a range of countries around the world and certainly we’ll continue those conversations,” she said. Asked why Mexico and Canada were chosen, the administration official said: “They are our neighbors, they are our partners.” ‘MORE WORK TO DO’ Mexican President Andres Manuel Lopez Obrador had requested the vaccine previously. The official said the countries were in touch about the vaccine loan. “We’ve been working through the diplomatic channels,” he said. “We’re having positive conversations with the U.S. Those conversations are fairly advanced but there’s more work to do,” a senior Canadian government source said. Reports of blood disorders have prompted more than a dozen nations to suspend use of AstraZeneca’s vaccine but on Thursday the European Union’s drug watchdog said that after an investigation it is still convinced the benefits of that vaccine outweigh the risks. A spokeswoman for AstraZeneca declined to comment on the deal but noted that its doses in the United States were owned by the U.S. government. Biden has said if the United States has a surplus of vaccine, it will share it with the rest of the world. The White House has focused on vaccinating people in the United States, which has seen more than 530,000 people die from virus. The country is getting prepared to roll out the AstraZeneca vaccine domestically if it gets authorization from the U.S. Food and Drug Administration, the White House said. The United States has pledged $4 billion to the global COVAX vaccine program that aims to deliver coronavirus vaccines to poor countries. The United States does not need the AstraZeneca shots to meet its target of having enough doses for all U.S. adults by the end of May. The three authorized vaccine makers – Pfizer Inc/BioNTech SE, Moderna Inc, and Johnson & Johnson – have promised to deliver nearly 500 million doses to the United States by then. The U.S. decision to loan the AstraZeneca doses comes as Mexico has in recent weeks leaned increasingly on China and Russia to secure vaccines to carry out its inoculation plans.