Contraindications for Yellow Fever Vaccine

Absolute Contraindications

• The Centers for Disease Control and Prevention recommends that yellow fever vaccine is absolutely contraindicated in infants younger than 6 months, persons with thymus disorders associated with abnormal immune cell function, severe immunosuppression due to HIV/AIDS (CD4 <200/mm³), primary immunodeficiencies, malignancies, transplantation, and those on immunosuppressive medications 1, 2, 3
• Infants younger than 6 months of age are at significantly elevated risk of yellow fever vaccine-associated neurotropic disease (YEL-AND) 4, 5
• Thymus disorders associated with abnormal immune cell function, such as thymoma or myasthenia gravis, are absolute contraindications for the vaccine 6
• Persons with AIDS or symptomatic HIV infection should not receive the vaccine 1, 2
• HIV-infected individuals with CD4 counts <200/mm³ (or <15% of total lymphocytes for children <6 years) are at increased risk and should not receive the vaccine 3, 7
• Primary immunodeficiencies, malignant neoplasms, and transplantation recipients are also contraindicated for the vaccine 7
• Immunosuppressive or immunomodulatory therapies, including high-dose systemic corticosteroids, alkylating drugs, antimetabolites, TNF-α inhibitors, and IL-1 blocking agents, are contraindicated for the vaccine 7, 8, 9

Important Exceptions and Clarifications

• The Centers for Disease Control and Prevention recommends that yellow fever vaccine can be administered to individuals on short-term corticosteroid use (<2 weeks), low-to-moderate dose (<20 mg prednisone or equivalent per day), long-term alternate-day treatment with short-acting preparations, maintenance physiologic doses (replacement therapy), or topical administration (skin, eyes), inhaled, or intra-articular, bursal, or tendon injections 8, 9

Clinical Management When Vaccination is Contraindicated

• For patients with contraindications who must travel to yellow fever endemic areas, a medical waiver should be provided and emphasis should be placed on protective measures against mosquito bites 3, 7

Special Considerations

• Egg-sensitive individuals can undergo skin testing before vaccination, and desensitization protocols can be implemented if necessary 5
• All vaccine recipients should be observed for at least 15 minutes following administration and epinephrine (1:1000) should be readily available to manage potential anaphylactic reactions 5

Thymus Removal and Immunocompromised Status

Critical Distinction: Context of Thymus Removal

• The Centers for Disease Control and Prevention (CDC) states that individuals who underwent incidental surgical thymus removal are not considered immunocompromised and can receive live vaccines, but those with thymus removal for thymoma or myasthenia gravis require careful evaluation as they may have underlying immune dysfunction 10
• Patients who had incidental thymus removal during cardiac surgery or other procedures can receive yellow fever vaccine and other live vaccines without restriction, as they maintain adequate immune function through existing peripheral T-cell populations 10
• The CDC explicitly states that incidental surgical thymus removal or remote radiation therapy to the thymus does not constitute immunodeficiency for vaccination purposes 10
• Yellow fever vaccine is absolutely contraindicated in persons with thymus disorders associated with abnormal immune cell function, such as thymoma or myasthenia gravis, according to the CDC 10
• Four of the initial 23 cases of yellow fever vaccine-associated viscerotropic disease occurred in patients who had thymectomies for thymomas, highlighting the importance of careful evaluation in these patients 10
• The underlying thymus disorder itself—not the removal—creates the immune dysfunction, as stated by the CDC 10
• For patients with a history of thymectomy, the CDC recommends determining the indication for thymectomy and evaluating for immune dysfunction in those with thymoma or myasthenia gravis 10
• The CDC advises against assuming all thymectomy patients are immunocompromised, as the vast majority with incidental removal maintain normal immune function 10
• The CDC also warns against overlooking the underlying thymus disorder (thymoma, myasthenia gravis) as the primary source of immune dysfunction rather than the surgical removal itself 10