Thermostability and efficacy in the field of a new, stabilized yellow fever virus vaccine.

Samples of the new, stabilized 17D virus vaccine from Pasteur Vaccins, France were stored for up to six months at +10 +/- 2 degrees C in the hospital of Bouar, Central African Republic. Each month during this study, the vaccine ampoules were put into an ice box without ice and taken into the field to be used as part of a vaccination programme. No significant loss of infectious virus titre was observed under these conditions. Efficacy of the vaccine was determined from percent seroconversions in vaccinated children. No loss of efficacy of the vaccine was observed after five months storage at +10 degrees C and five trips in the field, confirming the high heat stability of the new vaccine.