

WASHINGTON — When President Biden pledged last week to amass enough vaccine by late May to inoculate every adult in the United States, the pronouncement was greeted as a triumphant acceleration of a vaccination campaign that seemed to be faltering only weeks earlier.
And it is true that production of two of the three federally authorized vaccines has sped up in part because of the demands and directives of the new president’s coronavirus team.
But the announcement was also a triumph of another kind: public relations. Because Mr. Biden had tamped down expectations early, the quicker timetable for vaccine production conjured an image of a White House running on all cylinders and leaving its predecessor’s effort in the dust.
A closer look at the ramp-up announced last week offers a more mixed picture, one in which the new administration expanded and bulked up a vaccine production effort whose key elements were in place when Mr. Biden took over for President Donald J. Trump. Both administrations deserve credit, although neither wants to grant much to the other.
the Korean War-era Defense Production Act, the federal government could help Pfizer obtain the heavy machinery it needed to expand its plant in Kalamazoo, Mich. The Trump administration had repeatedly invoked that law, but its order for Pfizer only covered single-use supplies like plastic liners, not durable factory equipment.
Crucially, Mr. Biden’s top aides drove another vaccine manufacturer, Johnson & Johnson, to force a key subcontractor into round-the-clock operations so its vaccine could be bottled faster. That company had fallen behind on the production targets laid out in its federal contract. Only after Jeffrey D. Zients, the White House’s chief pandemic adviser, and Dr. David Kessler, who oversees the vaccine effort, demanded the company commit more resources did it publicly pledge to meet a crucial deadline in May.
At the same time, though, Mr. Biden benefited hugely from the waves of vaccine production that the Trump administration had set in motion. As both Pfizer and Moderna found their manufacturing footing, they were able to double and triple the outputs from their factories.
Mr. Biden had been in office less than a month when Moderna announced that it could deliver 200 million doses by the end of May, a month earlier than scheduled, simply because it had become faster at production. Pfizer was able to shave off even more time, moving up the timetable to deliver its 200 million doses by a full two months, partly because of newfound efficiencies and partly because it was given credit for six doses per vial instead of five.
All this enabled Mr. Biden to announce that his administration would have enough doses in hand by the end of May to cover all 257 million adults, two months earlier than he had promised just a few weeks earlier. His aides noted that on Sunday, the nation hit a daily record of 2.9 million shots, three and a half times as many as were given on Inauguration Day.
announced its vaccine was robustly effective on Nov. 9, nearly a week after Election Day, then filed its application for emergency use authorization on Nov. 20.