Creating a safe and effective COVID-19 vaccine is just the first step. Recent media reports suggest that making it will also be a major challenge.

There are presently a number of vaccine candidates around the world that are showing promise and entering the clinical studies phase — a speed of development usually unheard of in the vaccine space. The fact that there is more than one potential vaccine showing promise is good: Experts say the world will likely need more than one approved vaccine to effectively scale up production.

But some of the promising vaccine candidates from companies such as Inovio and Moderna use cutting edge technology that has never been scaled up to produce millions of vaccine doses in factories, according to a recent report in The New York Times.

In the U.S., the White House has created a private-public partnership called Operation Warp Speed to build manufacturing capacity before clinical trials of vaccine candidates are even completed. The Defense Departement is taking a lead on manufacturing logistics. But Gen. Gustave F. Perna, who is in charge of the efforts, told the Times that discussions about needed equipment and facilities are just starting. He noted that finding the supplies and figuring out how to distribute them needs to happen at the same time.

Treasury Secretary Steven Mnuchin told The Hill yesterday that President Donald Trump is open to invoking the Korean War–era Defense Production Act to get companies to prioritize coronavirus vaccine manufacturing. Trump has already used the DPA to boost the manufacturing of respirators, ventilators and other equipment needed to treat the virus.

Countries around the world are making preparations. The U.K. government, for example, announced on May 17 that it is providing £131million (equivalent to $167 million) to the Vaccines Manufacturing and Innovation Centre (VMIC) so that it can produce 70 million vaccine doses in 4-6 months from after its expected summer 2021 opening.