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Who qualifies for a third dose of COVID-19 vaccine?

U.S. health regulators have authorized an extra dose of the Pfizer or Moderna COVID-19 vaccines in people with weakened immune systems to better protect them from the virus.
U.S. health regulators have authorized an extra dose of the Pfizer or Moderna COVID-19 vaccines in people with weakened immune systems to better protect them from the virus.

Americans at high risk from COVID-19 because of severely weakened immune systems are now allowed to get a third vaccination in hopes of better protection, a policy change endorsed Friday by influential government advisers.

The Food and Drug Administration ruled that transplant recipients and other similarly immune-compromised patients can get a third dose of either the Pfizer or Moderna vaccine. But the decision offers an extra dose only to those high-risk groups — not the general public.

These patients have been clamoring for months for better protection, some of them traveling across state lines or lying to get another dose. About 1.1 million people already have gotten at least a third dose of the Pfizer or Moderna vaccines on their own, the Centers for Disease Control and Prevention revealed, although it’s not clear how many did so because they had weakened immune systems.

Advisers to the CDC grappled Friday with exactly who qualifies before unanimously endorsing the FDA’s decision.

Here are some things to know:

WHY DO SOME PEOPLE NEED AN EXTRA DOSE?

The Pfizer and Moderna vaccines offer powerful protection for otherwise healthy people, but many who take immune-suppressing medications or have diseases that tamp down their immune systems generally get less benefit from the standard two doses. The CDC cited one study suggesting about 40% to 44% of people hospitalized for a so-called breakthrough case — infection after vaccination — are among the immune-compromised.

Those hospitalized patients “did all the right things -- they’re just suffering from a lack of good vaccine protection,” said Dr. Camille Kotton of Massachusetts General Hospital, one of CDC’s advisers.

WHO QUALIFIES?

Roughly 7 million American adults are classified as immune-compromised, but the FDA singled out transplant recipients and others with similar levels of immune suppression. The FDA didn’t spell out exactly who falls into those other categories. But according to the CDC, people with blood cancers, those taking certain cancer chemotherapies, and those taking certain medications such as rituximab for rheumatoid arthritis tend to have especially poor responses to vaccination.

ARE THERE AGE RESTRICTIONS?

For now, the new policy allows a third dose of the Pfizer vaccine for children as young as 12 who also meet the high-risk requirement, but adults only for a third Moderna dose. That’s because the Pfizer vaccine currently is the only authorized option for Americans under 18. That could change if Moderna’s vaccine eventually is allowed for teens.

WILL I NEED A DOCTOR’S NOTE OR A BLOOD TEST?

The government isn’t requiring either — patients will just need to tell the vaccine provider why they’re seeking another dose. “We would want to make that as easy as possible,” said Dr. William Schaffner, an infectious diseases expert at Vanderbilt University.

WHAT WILL A THIRD DOSE COST?

Shots given under FDA’s emergency use authorization are free.

IS MIX-AND-MATCH ALLOWED?

The government encourages the third dose to be the same as the first two, but doesn’t mandate it.

HOW WELL DOES A THIRD DOSE WORK?

It helps at least some people. Canadian researchers this week reported 55% of transplant recipients given a third dose two months after standard vaccination had good antibody levels compared to 18% who were given a dummy third shot for comparison. Health experts urged these high-risk patients to continue masking and taking other precautions since there’s no guarantee a third dose will work.

Dr. Jonathan Kantor, a Jacksonville epidemiologist, said patients can expect side effects similar to the second dose.

“That third shot is going to be similar to the second shot, so for those who’ve had a Moderna or Pfizer vaccine before. It’s not going to be like the first shot with a just a sore arm, you may end up feeling icky from that,” Kantor said.

WHAT IF A THIRD DOSE STILL DOESN’T WORK?

It’s not a substitute for vaccination, but the FDA has authorized an antibody treatment as a preventive treatment if high-risk patients are exposed to the virus. And it’s critical for family members and others close to fragile patients to be vaccinated.

More research is underway to better tease out whether some immune-compromised patients need still other options, such as carefully monitored changes to their medications.

WHAT IF I HAD THE SINGLE-DOSE JOHNSON & JOHNSON VACCINE?

There’s little data on how another dose works in high-risk people who received that vaccine, although it’s likely a small number since fewer than 14 million Americans overall have received the J&J shot. Still, CDC counts at least 90,000 who have gotten another dose on their own.

“The Johnson and Johnson shot isn’t mentioned at all in the FDA announcement, that’s probably because they don’t have the date they want to jump to that point,” said Kantor. “The reason they made that announcement when they did is a New England Journal of Medicine article, explaining just how effective it can be boosting that immune response.”

FDA vaccines chief Dr. Peter Marks said the agency is working to get more information about immune-suppressed J&J patients but that for now, the evidence only backs a recommendation of extra doses for Pfizer and Moderna recipients with fragile immune systems.

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The Associated Press Health and Science Department receives support from the Howard Hughes Medical Institute’s Department of Science Education. The AP is solely responsible for all content.


About the Authors:

Tarik anchors the 4, 5:30 and 6:30 p.m. weekday newscasts and reports with the I-TEAM.