YF-VAX (Yellow Fever Vaccine) - Warnings and Precautions

WARNINGS

Anaphylaxis may occur following the use of YF-VAX®, even in individuals with no prior history of hypersensitivity to the vaccine components.

EPINEPHRINE INJECTION (1:1000) SHOULD ALWAYS BE IMMEDIATELY AVAILABLE IN CASE OF AN UNEXPECTED ANAPHYLACTIC OR OTHER SERIOUS ALLERGIC REACTION.

Yellow fever vaccines must be considered as a possible, but rare, cause of vaccine-associated viscerotropic disease²(previously described as multiple organ system failure),^2,24 that is similar to fulminant yellow fever caused by wild type yellow fever virus. Available evidence suggests that the occurrence of this syndrome may depend upon the presence of undefined host factors, rather than intrinsic virulence of the yellow fever strain 17D vaccine viruses isolated from subjects with vaccine-associated viscerotropic disease.^24-27(See ADVERSE REACTIONS section).

Vaccine-associated neurotropic disease²(previously described as post-vaccinal encephalitis¹) is a known rare adverse event associated with yellow fever vaccination. Age less than 9 months and immunosuppression are known risk factors for this adverse event. (See CONTRAINDICATIONS and ADVERSE REACTIONS sections).

PRECAUTIONS

GENERAL

Prior to an injection of any vaccine, all known precautions should be taken to prevent adverse events. The patient's previous immunization history, current health status, and medical history should be reviewed for previous hypersensitivity reactions and other adverse events related to this vaccine or similar vaccines and for possible sensitivity to dry natural latex rubber. The stopper of the vial contains dry natural latex rubber that may cause allergic reactions. In some instances where symptoms appear soon after a vaccine is administered, differentiation between allergic reaction to the vaccine and reaction to an environmental allergen may not be possible. ²²

EPINEPHRINE INJECTION (1:1000) SHOULD ALWAYS BE IMMEDIATELY AVAILABLE IN CASE OF AN UNEXPECTED ANAPHYLACTIC OR OTHER SERIOUS ALLERGIC REACTION.

A separate, sterile syringe and needle should be used for each patient to prevent transmission of hepatitis or other infectious agents from person to person. Needles should not be recapped and should be properly disposed (eg, sterilized or disposed in red hazardous waste containers).

HYPERSENSITIVITY REACTIONS

YF-VAX® should not be administered to an individual with a history of hypersensitivity to egg or chicken protein (see CONTRAINDICATIONS section). However, if a subject is suspect as being an egg-sensitive individual, the following test can be performed before the vaccine is administered: ²²

1. Scratch, prick, or puncture test: Place a drop of a 1:10 dilution of the vaccine in physiologic saline on a superficial scratch, prick, or puncture on the volar surface of the forearm. Positive (histamine) and negative (physiologic saline) controls should also be used. The test is read after 15 to 20 minutes. A positive test is a wheal 3 mm larger than that of the saline control, usually with surrounding erythema. The histamine control must be positive for valid interpretation. If the result of this test is negative, an intradermal (ID) test should be performed.
2. Intradermal test: Inject a dose of 0.02 mL of a 1:100 dilution of the vaccine in physiologic saline. Positive and negative control skin tests should be performed concurrently. A wheal 5 mm or larger than the negative control with surrounding erythema is considered a positive reaction.

If vaccination is considered essential, despite a positive skin test, then desensitization can be considered (see DOSAGE AND ADMINISTRATION section, Desensitization subsection).

INFORMATION FOR PATIENTS

Prior to administration of YF-VAX®, potential vaccinees or their parents or guardians should be asked about their recent health status. All potential vaccinees or their parents or guardians should be fully informed of the benefits and risks of immunization and potential for adverse events that have been temporally associated with YF-VAX® administration. Vaccinees or their parents or guardians should be instructed to report all serious adverse events that occur up to 30 days post-vaccination to their health-care provider.

All travelers should seek information regarding vaccination requirements by consulting local health departments, the Centers for Disease Control and Prevention (CDC), and WHO. Travel agencies, international airlines, and/or shipping lines may also have up-to-date information. Such requirements may be strictly enforced, particularly for persons traveling from Africa or South America to Asia. Travelers should consult the latest published version of Health Information for International Travel to determine requirements and regulations for vaccination.²³

An International Certificate of Vaccination should be completed, signed, and validated with the center's stamp where the vaccine is administered and provided to all vaccinees. The immunization record should contain the date, lot number and manufacturer of the vaccine administered. ^28-30 Subjects should be told that US vaccination certificates are valid for a period of 10 years commencing 10 days after initial vaccination or revaccination.

DRUG INTERACTIONS

Data are limited in regard to the interaction of YF-VAX® with other vaccines.

• Measles (Schwartz strain) vaccine, diphtheria and tetanus toxoids and pertussis vaccine adsorbed (DTP), ³¹ Hepatitis A and Hepatitis B vaccines, ^2,12,32,33 meningococcal vaccine, Menomune® - A/C/Y/W-135, and typhoid vaccine, Typhim Vi®, ^2,12,32 have been administered with yellow fever vaccine at separate injection sites.
• No data exist on possible interference between yellow fever and rabies or Japanese encephalitis vaccines. ²
• In a prospective study, persons given 5 cc of commercially available immune globulin did not experience alterations in immunologic responses to the yellow fever vaccine.^2,34
• The anti-malarial drug chloroquine has been administered with yellow fever vaccine.^2,35

PATIENTS ON CORTICOSTEROID THERAPY

Oral Prednisone or other systemic corticosteroid therapy may have an immunosuppressive effect on recipients of yellow fever vaccine that potentially decreases immunogenicity and increases the risk of adverse events (see CONTRAINDICATIONS section). Intra-articular, bursal, or tendon injections with Prednisone or other corticosteroids should not constitute an increased hazard to recipients of yellow fever vaccine.

PATIENTS WITH ASYMPTOMATIC HIV INFECTION

Subjects with asymptomatic HIV infection who have had recent laboratory verification of adequate immune system function and who cannot avoid potential exposure to yellow fever virus should be offered the choice of vaccination. Vaccinees should be monitored for possible adverse effects. The seroconversion rate to 17D vaccines is likely to be reduced in these patients. ¹⁷ Therefore, documentation of a protective antibody response is recommended before travel. (See CLINICAL PHARMACOLOGY section.) For discussion of this subject and for documentation of the immune response to vaccine where it is deemed essential, the CDC may be contacted (970) 221-6400.

CARCINOGENESIS, MUTAGENESIS, IMPAIRMENT OF FERTILITY

YF-VAX® has not been evaluated for its carcinogenic or mutagenic potential or its effect on fertility.

PREGNANCY

REPRODUCTIVE STUDIES -- PREGNANCY CATEGORY C

Animal reproduction studies have not been conducted with YF-VAX®. It is also not known whether YF-VAX® can cause fetal harm when administered to a pregnant woman or can affect reproductive capacity. Because of the lack of large-scale controlled studies to verify its safety in pregnancy, YF-VAX® should be given to a pregnant woman only if clearly needed. The seroconversion rate to 17D vaccines is markedly reduced in pregnant women. (See CLINICAL PHARMACOLOGY section.)¹⁸ For discussion of this subject and for documentation of a protective immune response to vaccine where it is deemed essential, the CDC may be contacted at (970) 221-6400.

NURSING MOTHERS

It is not known whether this vaccine is excreted in human milk. There have been no reports of adverse events or transmission of 17D vaccine virus from nursing mother to infant. However, vaccination of nursing mothers should be avoided when possible, because of the theoretical risk of the transmission of 17D virus to the breast-fed infant. When travel of nursing mothers to high-risk yellow fever endemic areas cannot be avoided or postponed, such individuals may be immunized.

PEDIATRIC USE

Vaccination of infants less than 9 months of age IS CONTRAINDICATED because of the risk of encephalitis. (See CONTRAINDICATIONS and ADVERSE REACTIONS sections.)

GERIATRIC USE

Vaccination of subjects greater than 65 years of age should be limited to individuals who are traveling to or reside in known yellow fever endemic or epidemic areas, because of the increased risk for systemic adverse events in this age group. When vaccination is deemed necessary, the health status of such individuals should be evaluated prior to vaccination. Additionally, if vaccinated, elderly subjects should be carefully monitored for adverse events for 10 days post-vaccination (see ADVERSE REACTIONS section).^36,37