Mayor Bill de Blasio got part of his wish on Friday, as the Biden administration confirmed that it would be using the Defense Production Act to speed up the manufacturing of the COVID-19 vaccines created by Pfizer-BioNTech.

Under these orders, Pfizer will receive priority access to specialty pumps and filters that the pharmaceutical company needs to make its vaccine. The change means that any U.S. company producing this hardware must first honor their contracts with Pfizer before anyone else.

“One of the factors constraining increased manufacturing of the vaccines is limited equipment and ingredients,” Tim Manning, the Biden administration’s COVID-19 supply coordinator, said during a press briefing Friday. The initiative will also contract six companies to deliver 60 million at-home tests by the summer—a decision coming just days after the White House purchased 8.5 million similar tests for its stockpile. It also plans to build new factories for making gloves and other personal protective equipment.

The move comes as city and state officials work to iron out the many kinks in their vaccine distribution operations and stare down a large problem outside their control: A lack of supply.

Over the past couple weeks, Mayor Bill de Blasio has been urging the Biden administration and pharmaceutical companies to increase vaccine production by making greater use of the Defense Production Act, a Cold War-era law that allows the government to mobilize private companies during emergencies that threaten national security.

“We need wartime mass production here in America. Every lab should have the freedom to manufacture the COVID-19 vaccine,” de Blasio said in a statement issued February 2nd. “New York City has the infrastructure in place to vaccinate millions in the next few months. We just need the supply!”

Pfizer and Moderna are operating at full capacity, pumping out millions of doses of their COVID-19 vaccines each week. Yet, production still appears to be lagging behind and can’t keep up with demand. Delayed vaccine shipments from the federal government have already led to mass appointment cancellations and planning difficulties in New York and contributed to the city falling short of de Blasio’s goal of administering 1 million doses by the end of January.

Other promising vaccine candidates are in the pipeline, such as the one from Johnson & Johnson that’s now under review with the U.S. Food and Drug Administration, but some say more needs to be done to increase supply.

President Joe Biden announced last month that he will take advantage of the DPA to combat COVID-19 and some observers say it’s a powerful tool in the president’s arsenal.

But according to the New York Times, vaccine industry experts and manufacturers “have said that at least in the short term, using the Defense Production Act will not significantly increase supply, although every little bit could help.”

So what is the DPA and what can it actually do to boost the vaccination effort?

“The DPA provides the government with a menu of potential authorities to use,” says Deborah Pearlstein, a law professor at Cardozo specializing in national security. “The one that is most commonly used is so-called prioritization authority,” which allows the federal government to compel a company it’s contracting with to prioritize its contract ahead of any others.

The DPA also authorizes the federal government to determine how companies allocate supplies, provide financial incentives for companies to quickly ramp up production capacity, and coordinate voluntary collaboration among suppliers, providing them relief from antitrust laws.

First passed in 1950, the DPA was originally intended to give the president powers to influence private industry to engage in production for the purpose of bolstering national defense. Today, the law is routinely invoked for military purchasing as well as a range of other uses, such as speeding up infrastructure repairs after hurricanes.

“One of the ways in which the Biden administration could use the DPA is to prioritize supply chain contracts so that Pfizer can get the materials it needs faster to produce and distribute the vaccine,” Pearlstein said. “That is the kind of authority the DPA was designed to provide to enable the U.S. government to harness the productive capacity of private industry.”

Former President Donald Trump has been criticized for making narrow use of the law in a public health context. But in December, the Trump administration was reportedly nearing a deal with Pfizer to boost vaccine production that made use of the DPA to address supply chain issues.

According to the COVID-19 response plan Biden released in January, the government will use its contracting authorities under the DPA and other laws to improve the supply of COVID-19 protective gear and tests as well as to “strengthen the vaccination supply chain for raw materials and equipment and fill urgent vaccination-related supply and distribution gaps.”

Prior to Friday, the Biden administration specifically mentioned using the DPA to spur production of the “dead-space” needle syringes needed to extract extra doses out of bottles of the Pfizer vaccine.

Another supply chain issue the Biden administration hopes to use the DPA to address is the limited supply of lipid nanoparticles, which are used to provide protective casing for the fragile messenger RNA used in the Moderna and Pfizer vaccines. The technology the vaccines are using is still new and they have massively increased the demand for lipid nanoparticles, which were previously considered pretty niche. The companies that have contracted with Pfizer and Moderna to produce lipids already appear to be working at max capacity. CordenPharma, which manufactures lipids for Moderna, had to engineer a ten-fold increase in its capacity in 2020. It’s unclear how much untapped capacity exists elsewhere, given global vaccine demand.

Even if the DPA can be used to bolster the vaccine supply chain, though some industry experts are skeptical that it will significantly speed up vaccine production in the near term.

"The big problem is that even if you can get the raw material and get the infrastructure set up, how do you get a company that is already producing at maximum capacity to go beyond that maximum capacity?" Lawrence Gostin, a professor of global health law at Georgetown University, told Medscape.

Gostin and other vaccine industry experts interviewed by Medscape questioned whether it was feasible to efficiently transfer knowledge and technology from one vaccine manufacturer to another and quickly ramp up production. And Gostin said it would be “highly questionable legally” for Biden to compel such a transfer.

However, vaccine manufacturers have been voluntarily making themselves more open to collaboration than usual in order to boost capacity overseas. Swiss pharmaceutical company Novartis announced January 29th that it has signed an initial agreement with Pfizer and BioNTech to use its facilities to assist with vaccine production, and is in talks with other vaccine manufacturers to assist with production as well. For its part, Moderna made a pledge back in October not to enforce its COVID-19-related patents during the pandemic.

“This isn’t the moment to let the free market or shareholder value dictate what you do,” de Blasio wrote in a recent op-ed addressing pharmaceutical companies. “It is a moment to save lives.”