Merck & Co Inc will help make rival Johnson & Johnson’s COVID-19 vaccine in order to boost the slower-than-promised production of the one-dose shot, US President Joe Biden said on Tuesday.

Biden said the US government had invoked the Defense Production Act to help equip two Merck plants to make the J&J vaccine.

“One of the things that I learned when I came into office was that Johnson & Johnson was behind in manufacturing and production,” Biden said. “It simply wasn’t coming fast enough. So, my team has been hard at work to accelerate that effort.”

He said the plants already making J&J’s vaccine would also step up their output, producing 24 hours a day, 7 days a week.

An increased supply of the J&J vaccine sooner would speed up the US vaccination effort considerably, because you can inoculate twice as many people with the same number of shots.

The other two US-authorised vaccines produced by Pfizer Inc with partner BioNTech and Moderna Inc both require two shots a few weeks apart.

Biden said his administration has now secured enough vaccine for every adult in the United States to be vaccinated by the end of May.

Under its contract, J&J was supposed to deliver 12 million doses by the end of February, but had less than 4 million ready to ship when the vaccine was authorised on Saturday.

It expects to be able to deliver another 16 million doses by the end of this month – still well short of its previous commitments – but will not ship any next week.

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.

“We expect this manufacturing arrangement will enhance our production capacity so that we can supply beyond our current commitments,” J&J said in a statement.

The next shipments are waiting on regulatory approval of new manufacturing operations run by its partner, contract drug-maker Catalent Inc, J&J Chief Scientific Officer Paul Stoffels said in an interview on Monday.

Merck’s collaboration with New Jersey neighbor J&J comes after Merck scrapped development of its own COVID-19 vaccine candidates in January.

Merck last month said it was working on a deal to open up its manufacturing capacity to other vaccine makers.

Merck said on Tuesday it will also receive up to $268.8 million from the Biomedical Advanced Research and Development Authority (BARDA), a US agency charged with developing drugs and vaccines.

The funding is intended to help it to adapt and make available a number of its plants for COVID-19 vaccine and medicine production.

The partnership is the latest example of large drug-makers working together to help produce COVID-19 vaccines to meet global demand.

Swiss drug-maker Novartis signed an agreement in January to fill vials for the Pfizer/BioNTech shot, while French drug-maker Sanofi SA will help fill and pack millions of doses of Pfizer’s vaccine starting in July.