YELLOW FEVER VACCINE

From CDC

Yellow fever vaccine is a live-attenuated virus vaccine that has been available since the 1930s. No vaccine efficacy studies have been performed with yellow fever vaccine. However, the number of yellow fever disease cases was substantially reduced following the introduction of the vaccine supporting it being protective in humans.

Yellow Fever Vaccine Recommendations

Yellow fever vaccine is recommended for persons aged ≥9 months who are traveling to or living in areas at risk for yellow fever virus transmission in South America and Africa. Yellow fever vaccine may be required for entry into certain countries. Yellow fever vaccination requirements and recommendations for specific countries are available on the CDC Travelers' Health page.

Serious adverse events can occur following yellow fever vaccination. Therefore, persons should only be vaccinated if they are at risk of exposure to yellow fever virus or require proof of vaccination for country entry.

To minimize the risk of serious adverse events, healthcare providers should carefully observe the contraindications and consider the precautions about vaccination prior to vaccine administration (see below). A medical waiver can be given for persons with a precaution about or contraindication to vaccination. More information about medical waivers is available on the CDC Travelers' Health website.

For more information about the use of yellow fever vaccine in travelers or laboratory workers, see the Advisory Committee on Immunization Practice (ACIP) recommendations.

This vaccine is administered only at designated vaccination centers. Locations of centers are available from local health departments or at the CDC Travelers' Health Yellow Fever website. For healthcare professionals who want to learn more about yellow fever disease and vaccine, a continuing education module is available.

Booster doses of the vaccine

In February 2015, the CDC Advisory Committee on Immunization Practices (ACIP) approved a new recommendation that a single dose of yellow fever vaccine provides long-lasting protection and is adequate for most travelers. The updated recommendations also identify specific groups of travelers who should receive additional doses and others for whom additional doses may be considered including:

·                          Woman who were pregnant when first vaccinated

·                          Persons who received a hematopoietic stem cell transplant following their last dose of yellow fever vaccine

·                          Persons who are HIV-infected

·                          Travelers who received yellow fever vaccine at least 10 years previously and who will be in a higher-risk setting based on season, location, activities, and duration of their travel

·                          Laboratory workers who routinely handle wild-type yellow fever virus

The official ACIP recommendations were published on June 19, 2015 (see Advisory Committee on Immunization Practice (ACIP) recommendation) All current ACIP yellow fever vaccine recommendations can be found on the ACIP website.

Although ACIP no longer recommends booster doses of yellow fever vaccine for most travelers, clinicians and travelers should review the entry requirements for destination countries because changes to the International Health Regulations (IHR) have not yet been fully implemented. In 2014, the World Health Organization adopted the recommendation to remove the 10-year booster dose requirement from the IHR as of June 2016. Once this change is instituted, a completed International Certificate of Vaccination or Prophylaxis will be valid for the lifetime of the vaccine. Some countries have already adopted this change, which is noted under the yellow fever vaccine requirements on each country’s destination page . However, it is uncertain when and if all countries with yellow fever vaccination requirements will adopt this change.

Contraindications

·                          Allergy to a vaccine component

·                          Age <6 months

·                          Symptomatic HIV infection or CD4+ T-lymphocytes <200/mm3 (<15% of total in children aged <6 years)

·                          Thymus disorder associated with abnormal immune function

·                          Primary immunodeficiencies

·                          Malignant neoplasms

·                          Transplantation

·                          Immunosuppressive and immunomodulatory therapies

Precautions

·                          Age 6 to 8 months

·                          Age ≥60 years

·                          Asymptomatic HIV infection and CD4+ T-lymphocytes 200 to 499/mm3 (15-24% of total in children aged <6 years)

·                          Pregnancy

·                          Breastfeeding

Reactions to Yellow Fever Vaccine

Reactions to yellow fever vaccine are generally mild and include headaches, myalgias, and low-grade pyrexia. There have been reports of rare but serious events following yellow fever vaccination. These events include anaphylaxis, yellow fever vaccine-associated viscerotropic disease (YEL-AVD), and yellow fever vaccine-associated neurologic disease (YEL-AND). CDC can provide laboratory testing support for suspected YEL-AVD and YEL-AND cases.

Healthcare providers are encouraged to report all adverse events that might be caused by vaccination to the CDC/FDA Vaccine Adverse Events Reporting System (VAERS)