Anyone older than 12 can get one booster dose to combat waning immunity five months after the last shot in their primary series, regardless of which vaccine they received. Vaccines are not yet authorized for children younger than 5.

The CDC first recommended fourth shots for immunocompromised people in October. The agency has been working to educate pharmacists and other health providers since then, said CDC spokesperson Kristen Nordlund. Those efforts included a conference call with health officials from every state that had thousands of participants , as well as an additional call to physicians. The CDC has streamlined its website with booster advice several times. In its guidance to pharmacists, the CDC notes that patients don’t need to provide proof that they are immunocompromised.

Alyson Smith, who was turned away from a Walgreens drugstore after booking a vaccine appointment online, said she was pleased that the CDC is trying to help.

“I appreciate that the CDC is listening to patient and physician concerns and hope they will examine their processes for clear messaging and comprehensive dissemination of information,” Smith said.

In a statement before the publication of KHN’s first story, Walgreens said it continuously updates its pharmacists on new vaccine guidance.

Some leaders said the CDC should have done a better job of publicizing its advice on booster shots for the immunocompromised.

The call with pharmacists “should have been done many weeks ago,” said Dr. Eric Topol, founder and director of the Scripps Research Translational Institute. “I’m glad that the White House team is finally pushing forward on this.”

Dr. Ameet Kini, a professor of pathology and laboratory medicine at Loyola University Chicago Stritch School of Medicine, said he hopes the large pharmacies that have been turning people away will issue news releases and update their websites “explicitly stating that they are offering fourth doses ” to immunocompromised people. He said pharmacies also need to update their patient portals and provide “clear guidance for their pharmacists.”

Kaiser Health News is a national health policy news service. It is an editorially independent program of the Henry J. Kaiser Family Foundation which is not affiliated with Kaiser Permanente.