Even fractional dose of yellow fever vaccine provides long term protection

Intra-dermal administration of a one-fifth dose of yellow fever vaccine induced a protective immune response that lasted for 10 years after vaccination without requiring a booster dose.

The study published in the Annals of Internal Medicine revealed that fractional dose of 17D yellow fever virus (17D-YFV) vaccine has been shown to be non-inferior to the standard dose in inducing seroprotection.

Anna Roukens and associates conducted a study to evaluate whether fractional-dose vaccination can confer long-term immunity.

The randomized, controlled trial was conducted from 2005 to 2007 at Leiden University Medical Center in the Netherlands and included 75 participants who provided blood samples at 10-year follow-up after receiving either a 0.1-millilitre (mL) fractional dose of the vaccine intradermally or the standard 0.5-mL dose subcutaneously.

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Participants who received a booster dose during the 10-year follow-up were excluded from the study. Both groups received the same vaccine, manufactured by Sanofi Pasteur.

The study found that thirty-nine of 40 participants had protective levels of yellow fever–neutralizing antibodies more than 10 years after receiving a fractional dose of 17D-YFV vaccine compared with 34 of 35 in the standard-dose group.

In 2006, the World Health Organization (WHO) began the Yellow Fever Initiative, which entailed preventive mass vaccination campaigns in western Africa and ensured an emergency stockpile of vaccines. But because the production of the yellow fever vaccine takes 12 months and uses pathogen-free embryonated eggs, production is difficult during a substantial outbreak.

Yellow fever is an acute viral hemorrhagic disease transmitted by infected mosquitoes. The "yellow" in the name refers to jaundice that affects some patients. Symptoms of yellow fever include fever, headache, jaundice, muscle pain, nausea, vomiting, and fatigue. A small proportion of patients who contract the virus develop severe symptoms and approximately half of those die within 7 to 10 days.

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http://annals.org/aim/article-abstract/2716699/long-term-protection-after-fractional-dose-yellow-fever-vaccination-follow