Individuals with certain medical conditions are at increased risk of severe illness1 if they become infected with SARS-CoV-2, the virus that causes COVID-19, and as such are recommended by the Centers for Disease Control and Prevention (CDC) for vaccination in the first phases of vaccine roll-out. The CDC estimates that this group represents 81 million people, or 40% of those recommended to receive a COVID-19 vaccine in these initial phases. This is a substantial portion of the nation’s population and, with vaccine supply still limited, not all eligible people will be able to get vaccinated immediately. Indeed, most states have not yet opened up vaccine eligibility to those with high-risk medical conditions, although they represent some of the next in line. Yet, much like states have discretion in deciding when to prioritize groups for vaccination, they also can decide how to define them, including the list of medical conditions that will be considered. Further, states, and counties or cities within states, may differ in their implementation for this population.
We assessed how states are defining “high-risk medical conditions,” including whether they follow CDC’s recommendations or deviate in some way.  Overall, we found that there is wide variation across the country, including in the conditions listed by states, whether these are limited or allow for additional conditions to be considered, and how clearly the information is presented. Some states stick to the CDC’s list exactly, but most do not. It is also quite difficult to locate information.  Given the challenges and confusion with vaccine roll-out thus far, this variation and lack of clarity could have significant bearing on the ability of those with high-risk medical conditions, some of whom may be among the most vulnerable, to access the vaccine in early phases.

Table 1: Medical Conditions that Increase Risk of Severe Illness due to COVID-19
List 1: Adults of any age with the following conditions are at increased risk of severe illness due to COVID-19* List 2: Adults of any age with the following conditions might be at an increased risk for severe illness due to COVID-19
  • Cancer
  • Chronic kidney disease
  • COPD (chronic obstructive pulmonary disease)
  • Down Syndrome
  • Heart conditions, such as heart failure, coronary artery disease, or cardiomyopathies
  • Immunocompromised state (weakened immune system) from solid organ transplant
  • Obesity (body mass index [BMI] of 30 kg/m2 or higher but < 40 kg/m2)
  • Severe Obesity (BMI ≥ 40 kg/m2)
  • Pregnancy
  • Sickle cell disease
  • Smoking
  • Type 2 diabetes mellitus
  • Asthma (moderate-to-severe)
  • Cerebrovascular disease (affects blood vessels and blood supply to the brain)
  • Cystic fibrosis
  • Hypertension or high blood pressure
  • Immunocompromised state (weakened immune system) from blood or bone marrow transplant, immune deficiencies, HIV, use of corticosteroids, or use of other immune weakening medicines
  • Neurologic conditions, such as dementia
  • Liver disease
  • Overweight (BMI > 25 kg/m2, but < 30 kg/m2)
  • Pulmonary fibrosis (having damaged or scarred lung tissues)
  • Thalassemia (a type of blood disorder)
  • Type 1 diabetes mellitus
NOTES: Individuals in List 1 are recommended by the CDC for vaccination in phase 1c of vaccine roll-out.

The CDC’s Definition

The CDC maintains a “living” list of high-risk medical conditions that, based on available evidence, are linked to severe illness due to COVID-19. The list is divided into two parts (see Table 1):

  • Part 1: Medical conditions that have been shown to increase risk of severe illness
  • Part 2: Medical conditions that might increase risk but for which there are still limited data

At the same time, CDC notes that because this list only includes conditions with sufficient evidence, it is not exhaustive, and may not include every condition that increases risk of severe illness due to COVID-19, such as rare conditions for which there is limited evidence.

In December 2020, the CDC’s Advisory Committee for Immunization Practices (ACIP), charged with developing recommendations on how best to prioritize populations for COVID-19 vaccination in the context of limited supply, recommended that individuals with medical conditions that place them at increased risk of severe illness due to COVID-19 (conditions on Part 1 of CDC’s list) be prioritized in Phase “1c” by states. While states do not have to follow these recommendations, our previous analysis found that many initially did so, although several subsequently moved this group up to Phase “1b,” following Trump administration guidance1.  As of February 15, one state (PA) includes those with high-risk medical conditions in Phase 1a; 21 include them in Phase 1b; and 15 in Phase 1c.

Still, because of the slow vaccine roll-out, most states are not yet vaccinating those with high-risk medical conditions – as of February 15, just 17 states had opened up vaccine eligibility in part or in full to this group, while 34 have not. Over the next few weeks, it is expected that more states will expand eligibility to this group.


Our review of state vaccine prioritization documents finds that there is wide variation across the country, including in the conditions listed by states, whether these are limited or allow for additional conditions to be considered, and how clear and/or accessible the information is:

  • Among the 50 states and DC, 43 have provided information on how they would identify this population. Eight states are still developing their criteria and/or have not yet specified how they will define this group.
  • While most of the 43 states with information provide lists that specify at least some of medical conditions which are eligible for prioritization (or explicitly use the CDC’s list), six are quite vague and cannot be clearly assessed regarding any condition (e.g., they say “those with high-risk medical conditions” but do not include any further detail). Sometimes it is not clear if a state is referencing only Part 1 conditions, or both Part 1 and Part 2 conditions.
  • Among the 37 states listing or explicitly relying on/linking to CDC’s Part 1 list of conditions:
    • 14 include all twelve of the conditions on CDC’s list. (See Figure 1.)
    • Almost all include the following conditions: cancer (35), chronic kidney disease (34), COPD (37), heart conditions (35), immunocompromised due to solid organ transplant (36), sickle cell disease (35), and Type 2 diabetes (34).
    • There is less consistent inclusion of other conditions on the Part 1 list as follows: severe obesity (32 states), obesity (29), Down Syndrome (31), pregnancy (27), and smoking (16). Down Syndrome was added to the CDC’s Part 1 list on December 23, so it may be that states are not aware of this addition.
  • Among the 25 states listing or explicitly relying on/linking to CDC’s Part 2 list of conditions:
    • Only 6 states include all the conditions from CDC’s Part 2 list, 4 of which also include all conditions from list 1).
    • The most common conditions included are Type 1 diabetes (22) followed by immunocompromised state (19) and pulmonary fibrosis (16). Twelve states explicitly include HIV as part of those with an immunocompromised state; an additional 7 broadly include immunocompromised state, without specifying which conditions are included.
    • The conditions least commonly included were overweight (7), Cerebrovascular Disease (10) and Thalassemia (10).
  • Other findings:
    • In a few cases, people with disabilities are included in a state’s definition of high-risk medical conditions. For example, DE, MO, OH, and NY include those with intellectual and developmental disabilities broadly, and CA allows for provider discretion in determining if an individual has a developmental or other severe high-risk disability that makes them more likely to develop severe life-threatening illness or death from COVID-19, or acquiring COVID-19 will limit their care.
    • Some states phase in those with high-risk medical conditions by the number of conditions, setting or age, usually by prioritizing those with at least two conditions in an earlier phase (AZ, AK, CO, MA, MD, NH, ND, RI, SD, WA).
    • In some cases, states clearly note that eligibility is limited only to those conditions on the list while others do not, and several states specifically allow for provider discretion in determining conditions (CA, DC, MS, MT, NH, VA, TX).
    • Most states do not provide detail on if or how eligibility of health conditions will be confirmed. For the few that do, they indicate that they either will not require proof of eligibility or will rely on self-attestation (such as in MA, NJ, NY, NV, PA, OR, VA). At least one, however (NM), indicates that validation is required, either through a provider note, emergency department or hospital discharge summary, prescription, or other form of documentation.
    • Finally, information on the list of conditions included for prioritization is hard to find in many cases, often in multiple locations on a state’s website, in different documents, or otherwise inaccessible.


States have approached defining high-risk medical conditions much as they have approached other aspects of vaccine distribution – sometimes following federal guidelines, but often using their own definitions and criteria.  Adding to the confusion, the information is often hard to locate and, in some cases, not very clear, which could pose a barrier by limiting individuals’ ability to understand when they are eligible for vaccination.  People with high-risk medical conditions, some of whom may be among the most vulnerable, may be the least consistently defined group in the country, creating challenges in reaching them and getting them vaccinated.

Table 2: State Inclusion of CDC Part 1 Conditions

Table 3: State Inclusion of CDC Part 2 Conditions

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