The Trump administration and Pfizer are close to a deal under which the pharmaceutical company would bolster supply of its coronavirus vaccine for the United States by at least tens of millions of doses next year in exchange for a government directive giving it better access to manufacturing supplies, people familiar with the discussions said.

An agreement, which could be announced as early as Wednesday, would help the United States at least partly offset a looming vaccine shortage that could leave as many as 110 million adult Americans uncovered in the first half of 2021…

In the negotiations, the government is asking for 100 million additional doses from Pfizer from April through June. The company has signaled that it should be able to produce at least 70 million, and perhaps more, if it can get more access to supplies and raw materials.