The Biden administration on Tuesday announced a new strategy to stretch the limited available doses of the Jynneos monkeypox vaccine by changing how the vaccine is injected.

The new method would split up the doses and use one-fifth as much vaccine per shot. The partial dose of the vaccine would be injected into the upper layer of skin, rather than the full dose into the underlying fat, which is how shots are typically administered.

The strategy was first outlined last week by Food and Drug Administration (FDA) Commissioner Robert Califf, who said the intradermal injection method would allow officials to administer more shots without compromising the safety or effectiveness of the vaccine.

“In recent weeks the monkeypox virus has continued to spread at a rate that has made it clear our current vaccine supply will not meet the current demand,” Califf said in a statement. “By increasing the number of available doses, more individuals who want to be vaccinated against monkeypox will now have the opportunity to do so.”

In order to allow the FDA to authorize the new strategy, the Department of Health and Human Services first issued a determination allowing the agency to take emergency measures based on the information currently available about the monkeypox virus.

The Biden administration is scrambling to try to control the spiraling monkeypox epidemic, which has become both a political and public health concern. More than 8,900 cases have been reported, and experts think that’s likely an undercount. 

The move is aimed at alleviating a major shortage of Jynneos, the only FDA-approved vaccine for monkeypox. The administration has hundreds of thousands of doses available but will need millions in order to vaccinate everyone most at risk.

The Biden administration is under intense criticism for its response to the outbreak. Critics say officials were too slow to ship the vaccine that was ready to use and even slower to recognize the magnitude of the outbreak in order to get more shots ready to use.    

The U.S. has already purchased much of the global supply of Jynneos, but much of it is stored frozen in bulk substance at the manufacturer in Denmark. It needs to undergo a process called “fill and finish” to put the vaccine into usable vials to be shipped and then administered.