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Your Guide To Adult Vaccines

What Underlying Health Conditions Qualify for a Booster Shot?

Millions of adults under 65 are eligible for a third COVID-19 vaccine dose for medical reasons

woman in a doctor's office about to get her vaccine booster

Milan Markovic / Getty Images

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Booster shots for Pfizer vaccine recipients are here, and millions of Americans who completed the initial series at least six months ago are now eligible for the extra dose, including adults under 65 with a range of underlying health conditions.

The decision to cover this group in the booster criteria “reflect[s] the potential increase for severe outcomes” that a person with a chronic disease or other medical condition could experience if they get COVID-19, Centers for Disease Control and Prevention (CDC) Director Rochelle Walensky, M.D., explained in a Sept. 24 briefing on boosters.

Emerging research shows that while the vaccines still provide strong protection against hospitalization and death from COVID, their defense against infection begins to wane over time, especially in older adults, who are more likely to get sick if they contract the virus. That is why all adults 65 and up are encouraged to get the booster shot. But Walensky said the data on sustained vaccine effectiveness “are harder to parse out for those with underlying conditions” — another group that has been at high risk for severe COVID-19 since the start of the pandemic. “But we’re starting to see those data both here and in other countries,” she added.

For that reason, the CDC is recommending that adults ages 50 to 64 with the following health conditions get the booster shot if they had the Pfizer vaccine; people 18 to 49 who fall into this category also qualify for the booster, but are encouraged to assess their own risk and consult with a health care provider for advice:

  • Cancer
  • Chronic kidney disease
  • Chronic lung diseases, including COPD (chronic obstructive pulmonary disease), asthma (moderate to severe), interstitial lung disease, cystic fibrosis and pulmonary hypertension
  • Dementia or other neurological conditions
  • Diabetes (type 1 or type 2)
  • Down syndrome
  • Heart conditions (such as heart failure, coronary artery disease, cardiomyopathy or high blood pressure)
  • HIV infection
  • Immunocompromised state (weakened immune system)
  • Liver disease
  • Overweight (BMI greater than 25 and under 30) and obesity (BMI of 30 and above). Measure your BMI on
  •  Pregnancy
  • Sickle cell disease or thalassemia
  • Smoking, current or former
  • Solid organ or blood stem-cell transplant
  • Stroke or cerebrovascular disease, which affects blood flow to the brain
  • Substance use disorders

About 41.4 million adults in the U.S. under the age of 65 have a medical condition that makes them more likely to experience complications from COVID-19, according to a 2020 analysis from the Kaiser Family Foundation. And about 40 percent of the adult population is living with more than one chronic disease, the CDC says. The reasons these conditions make people more vulnerable to COVID-19 run the gamut, although impaired immune function is a common explanation.

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Health officials say younger and otherwise healthy adults don’t need a booster shot now, but recommendations could change in the future. Americans of all ages and conditions who received the Moderna or Johnson & Johnson vaccines also need to wait on the booster. Both companies are working on bringing their own booster shots to the public, but experts say it could be a few more weeks before the necessary regulatory approvals from the Food and Drug Administration (FDA) and CDC fall into place.

Who Qualifies for Pfizer’s Booster Shot?

The CDC recommends the following people get a COVID-19 booster at least six months after getting shots one and two in the Pfizer-BioNTech series:

  • ​People 65 and older and residents in long-term care settings
  • People ages 50 to 64 with underlying medical conditions
  • People ages 18 to 49 with underlying medical conditions, based on their individual benefits and risks
  • People ages 18 to 64 who are at increased risk for COVID-19 exposure and transmission because of their occupation (first responders, health care workers, teachers, manufacturing workers, food and agricultural workers, U.S. Postal employees, etc.), based on their individual benefits and risks

Rachel Nania writes about health care and health policy for AARP. Previously she was a reporter and editor for WTOP Radio in Washington, D.C. A recipient of a Gracie Award and a regional Edward R. Murrow Award, she also participated in a dementia fellowship with the National Press Foundation.​