WASHINGTON — A White House proposal to mail masks to Americans may be targeted at schools or communities that are particularly vulnerable to the spread of the coronavirus, rather than to all U.S. households, multiple senior administration officials said. The Biden administration has been looking into the logistics of sending masks directly to all Americans for more than a week, and in recent days the discussions have coalesced around the notion that a more narrowly targeted effort could be more effective, the officials said. Two officials said the administration could decide to ship masks to both vulnerable communities and schools. An official said "vulnerable communities" include seniors and areas with high rates of coronavirus infections. No final decision has been made about whether to send any masks to Americans or what the scope might be, officials said. The timing of a possible announcement also has not been set, officials said. The White House declined to comment. The White House has faced criticism that its goal to reopen schools during President Joe Biden's first 100 days in office — at least one day a week of in-person learning — is unambitious. A new Centers for Disease Control and Prevention report also stresses the importance of wearing properly fitting masks, including the suggestion of placing cloth masks over medical masks. The idea of mailing masks to American households was explored and discarded by the Trump administration. NBC News was first to report last week that the Biden administration's Covid-19 Response Team had revived the idea and was studying the logistics of mailing millions of face coverings to U.S. homes. White House press secretary Jen Psaki said Wednesday that "there are a range of options under consideration on to how to ensure that people who need masks the most, people who need this type of protection the most, receive it." The price tag for any effort to distribute masks is unknown, however — depending on how many masks the government planned to distribute, it could be hundreds of millions of dollars. The Department of Health and Human Services in May signed $640 million in contracts with textile manufacturers, including Hanes, to make masks, according to federal purchase records. Biden has made wearing masks a core part of his messaging campaign about the coronavirus. He and his staff wear face coverings routinely in the White House and when appearing in public. He issued a mask mandate on federal property and has asked Americans to wear face coverings for his first 100 days in office.