The fourth “booster” dose is recommended for six months after the third “additional” dose for people with organ transplants, cancer or other conditions.
While most Americans who initially received two shots of the Pfizer or Moderna COVID-19 vaccines will be able to get a single booster shot when they are eligible, federal health guidelines will also allow a few million Americans with compromised immune systems to eventually get a fourth dose as early as next year. Back in August, the FDA and the Centers for Disease Control and Prevention authorized and recommended an for some “moderately and several immunocompromised” patients who were vaccinated with two doses of Moderna or Pfizer. Now some of those people will be eligible to receive a fourth shot — a “booster” six months after they received their third “additional” dose. That group includes people who are taking medications that can suppress their immune systems for organ transplants or cancer, the CDC says, as well as people facing significant immunodeficiency from diseases like advanced or untreated HIV. Around 3 million “additional” doses were administered under that guidance, before Pfizer’s booster shots for a broader group of Americans were authorized and recommended last month. Around 2.3% of American adults are immunocompromised, the CDC estimated in August, though only a fraction of these 7 million adults would need an “additional” dose. To date, close to 14 million Americans have now received either a “booster” or “additional” dose of COVID-19 vaccine. “We use the term ‘additional’ dose to refer to a subsequent vaccine dose in people who likely did not mount a protective immune response after their primary vaccination,” the CDC’s Dr.
