Hypersensitivity to the active substance or to any of the excipients listed in Description or to eggs or chicken proteins.
Severe hypersensitivity reactions (e.g., anaphylaxis) after a previous dose of any yellow fever vaccine.
Age less than 6 months (see Dosage & Administration and Precautions).
Immunosuppression, whether congenital, idiopathic or as a result of treatment with systemic steroids (greater than the standard dose of topical or inhaled steroids), radiotherapy or cytotoxic drugs.
History of thymus dysfunction (including myasthenia gravis, thymoma, thymectomy).
Symptomatic HIV infection.
Asymptomatic HIV infection when accompanied by evidence of impaired immune function (see Precautions).
Moderate or severe febrile illness or acute illness.