A turning point in speeding up that pledge came a few weeks ago, on a Sunday afternoon in early February, during a phone call with Johnson & Johnson executives that had been planned for 15 minutes but stretched for longer than an hour, two senior administration officials told NPR.
US President Joe Biden announced on Tuesday that ramped-up production of the new vaccine will ensure a sufficient supply of doses for every adult American by the end of May - two months earlier than expected.
Meanwhile, Biden predicted that there will be enough COVID-19 vaccine to go around for all USA adults by the end of May, moving up his previous goal by two months.
Biden's announcements quickly raised expectations for when the nation could safely emerge from the pandemic with the promise of speedier vaccinations, but even as he expressed optimism, Biden quickly tempered the outlook for a return to life as it was before the virus hit.
"We need vaccinators, people who put the shots in people's arms, millions of Americans' arms".
"We wrote our first story at The New York Times about a possible partnership between Merck and [Johnson & Johnson] for manufacturing on January 21", a reporter said to Psaki during Tuesday's press briefing.
"We're increasing the places where people can get vaccinated".
The officials said getting Merck involved will vastly increase production of the Johnson and Johnson vaccine in the "medium term".
Teachers aren't now eligible to get vaccinated in MA per the state's vaccine rollout, a frustration for educators and lawmakers alike.
The company has said it will be able to provide the full 100 million doses it has agreed to supply by its original midyear deadline.
Still it was not immediately clear when the effect of Merck's assistance would be reflected in supply.
So far three vaccines have received emergency use authorization. President Biden announced J&J would be running its USA facilities "24/7" to speed vaccine out the door.
"J&J manufacturing facilities will now begin to operate 24-7, and will use the Defense Production Act to expedite critical materials in vaccine production, such as equipment, machinery and supplies", Biden said.
The Biden administration is racing against variants of COVID-19 that could make the existing vaccines less effective. Merck halted its own plans to develop a coronavirus vaccine earlier this year, finding that their candidates were generating an inferior immune system response compared with other vaccines.
Merck has since said it was in talks to help other drug companies with vaccine production, but wouldn't say Tuesday whether other deals are imminent. Merck released a statement saying in part, "Merck remains steadfast in our commitment to contribute to the global response to the pandemic and to preparing to address future pandemics".