Regarding the yellow fever 17D vaccine, which statement is correct?

• A It is a purified subunit vaccine prepared from the viral envelope protein
• B It is cultivated in human diploid cells and is therefore free of egg protein
• C Booster doses are required every 10 years to maintain certification
• D It was derived from the wild-type Asibi strain by serial passage in chick embryos ✓

Explanation

The 17B strain was derived from the wild-type Asibi isolate by prolonged passage in mouse brain and then in chick embryo tissue culture, producing a live attenuated virus grown in embryonated eggs. Since 2016 WHO amended the International Certificate of Vaccination to be valid for the life of the person vaccinated, so decennial boosters are no longer required, eliminating option C. Because it is egg-grown, severe egg allergy is a precaution, contradicting option B.

Reference: Plotkin's Vaccines, 8th ed.

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Written and medically reviewed by the StethoPrep medical team.