US allows extra COVID vaccine doses for some. Now what?

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 as government advisers grappled with exactly who qualifies.

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 Friday — although it's not clear how many did so because they had weakened immune systems.

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...