WASHINGTON (NewsNation Now) — Retired doctors and nurses will be allowed to administer COVID-19 vaccines in the U.S. under new changes to a public health emergency law, a White House official said.

Jeff Zients, coordinator of President Joe Biden’s White House COVID-19 response team, announced Wednesday that the Health and Human Services Department is amending the Public Readiness and Emergency Preparedness Act, also known as the PREP Act.

The law allows the HHS secretary to issue a PREP Act declaration in response to a public health emergency, which provides immunity from certain liability claims.

Zients also said Wednesday that the law would be amended to allow “licensed doctors, nurse and other practitioners – who are licensed in their home states – to administer shots across state lines.”

“As the president said, we need to increase the number of places where people can get vaccinated and also at the same time increase the number of vaccinators,” he said in the team’s first weekly briefing. “This action by HHS today will help get more vaccinators in the field.”

The changes come after President Joe Biden announced his administration has ordered 200 million more coronavirus vaccines, and is planning to funnel more doses to states.

As of Wednesday morning, the Centers for Disease Control and Prevention reported that just over half of the 44 million doses distributed to states have been put in people’s arms. It’s well short the hundreds of millions of doses that experts say will need to be administered to achieve herd immunity and curb the outbreak.

The reason more of the available shots in the U.S. haven’t been dispensed isn’t entirely clear. Some state officials have complained of a lag between when they report their numbers to the government and when the figures are posted on the CDC website.

Meanwhile, some vaccination sites are canceling appointments because of shortages. Many are believed to be holding large quantities of vaccine in reserve to make sure people who have already gotten their first shot receive the required second one on schedule, three to four weeks later.

President Biden has said his administration would like to ramp-up vaccinations to 1.5 million a day.