President Joe Biden said that Merck & Co. will help make Johnson & Johnson’s single-shot coronavirus vaccine -- a collaboration between rivals aimed at ramping up the pace of inoculations that will help provide enough supply for every adult in the U.S. by the end of May.

Biden said at the White House that Merck will help produce key supplies to speed J&J’s production of the country’s first one-dose vaccine, which was authorized for use on Saturday.

“We should all be encouraged by this news,” Biden said Tuesday afternoon. “The more people that get vaccinated, the faster we’re going to overcome this virus.”

Biden said he hopes the U.S. would be back to normal “by this time next year” but said he’d been cautioned not to provide a specific date “because we don’t know for sure.”

Biden also called for state and local governments to prioritize teachers for vaccinations, as he pushes for schools to reopen safely with full-time classroom instruction.

Vaccinations are increasing, but a decline in new cases has stalled. Meanwhile, several states are lifting restrictions as new, more contagious variants spread -- threatening to reignite the pandemic before vaccines take hold.

Merck announced in January that it was shuttering its coronavirus vaccine program, redirecting resources to its COVID-19 therapeutics efforts instead. J&J’s vaccine has been beset by production delays, but now could prove a major boost to the U.S. vaccination effort -- it is much easier to ship and store than the Pfizer Inc. and Moderna Inc. products.

J&J had previously promised the U.S. 12 million doses by the end of February, but has delivered 3.9 million so far. It says it will deliver a total of 20 million by the end of the month.

Biden’s health team has been urging Americans to take whichever of the vaccines that is available to them first, in a move to head-off concerns or comparisons of their viability.

On Monday, J&J Chief Executive Officer Alex Gorsky said in an interview that the company was seeking additional manufacturing partnerships to ramp up production of its vaccine.

“We are doing everything we can partnering with the U.S. government and other external manufacturers to see what we can do to accelerate and increase” the number of doses, Gorsky said.