President Biden will announce Tuesday that pharmaceutical giant Merck will help Johnson & Johnson manufacture its newly authorized coronavirus vaccine to boost supply, a senior administration official tells Axios.

The big picture: The development has the potential to vastly increase supply, possibly doubling what the J&J could make on its own, the official said. The company has run into challenges while trying to expand its vaccine production to a global scale.

• Jeff Zients, the White House's COVID-19 response coordinator, said at a briefing Monday that 3.9 million doses of the J&J vaccine will be distributed to states, tribes, territories, pharmacies and community health centers this week, starting as early as Tuesday.

The state of play: Merck will dedicate two U.S. facilities for J&J shots, one to help place vaccine in vials and package and the other to make the vaccine itself. The Washington Post first reported the partnership.

• Merck's experience in vaccine production is vast, despite its discontinuation in developing its own vaccine against the coronavirus in January. It's the only supplier for the vaccine which protects children from measles, mumps and rubella.
• It developed Gardasil, which protects against the human papillomavirus and also received FDA approval for an Ebola vaccine in 2019.

Background: J&J’s vector-based COVID-19 shot, which received the FDA’s emergency use authorization on Saturday, was also recommended by the CDC a day later for people ages 18 years and older.

• Both Johnson & Johnson and Merck did yet not respond to a request for comment.