President Joe Biden today announced a partnership in which Merck (NYSE:MRK) will make Johnson & Johnson’s (NYSE:JNJ) recently approved COVID-19 vaccine.

Before Biden’s announcement,The Washington Post reported that the two competitors’ agreement will boost the supply of the single-dose vaccine from J&J’s Janssen subsidiary, which received FDA emergency use authorization last week.

According to the report, anonymous officials told The Post that, upon the realization that J&J was behind on vaccine production in the early days of the Biden administration, they began looking for additional manufacturing capacity, landing on Merck as an option after the company was unable to produce its own COVID-19 vaccine.

Merck is set to provide two U.S. facilities for producing J&J vaccine doses, with one offering fill-finish services and the other actually making the vaccine. According to the report, this could potentially double the production capacity of J&J by itself. The official told The Post that the normally competing companies see the unlikely alliance as a “wartime effort.”

The FDA issued EUA for J&J’s Ad26.COV2-S vaccine on Feb. 27, a day after an advisory panel unanimously recommended that the agency authorize the vaccine for adults 18 and over. J&J’s vaccine is the third COVID-19 vaccine to receive authorization in the U.S. so far, following the ones from Pfizer/BioNTech and Moderna. It is the first one available as a single dose and can be stored at typical refrigeration temperatures.

As of yesterday, there were 4 million doses of the vaccine being shipped by J&J, with plans to ship a total of 20 million by the end of March. That 20-million mark is 17 million fewer than expected under a government contract, according to The Post. However, the company says it is on track to deliver 100 million by the end of June.

“Literally it’s on trucks as we’re talking,” J&J CEO Alex Gorsky, speaking yesterday, told NBC’s Today Show.

Johnson & Johnson will make the vaccine available during the pandemic on “a not-for-profit basis.” The company is also conducting a trial for a two-dose regimen of its vaccine, but The Post said results are not expected until May.

The Post also reported that its sources indicated that Biden would utilize the Defense Production Act, which the Trump administration enacted last spring amidst the need for ventilators and other equipment, to give Merck priority for securing the equipment necessary for upgrading its facilities to produce J&J’s vaccine.

Late in the day on Tuesday, Biden confirmed the partnership between Merck and Johnson & Johnson in a press conference, indeed invoking the Defense Production Act. Biden said that, with the latest developments in vaccine production, the country is on track to have enough supply to vaccinate every American adult by May.