Stabilization of rinderpest vaccine by modification of the lyophilization process

Rinderpest (RP), a lethal disease of cattle, was almost eradicated from the African continent under Joint Project 15 (JP15), using an excellent modified live virus vaccine. Due to marked instability of the vaccine, a cold chain was required to ensure that the vaccine was potent at the time of application. Rinderpest re-emerged in the early 1980s. The Pan African Rinderpest Campaign (PARC) was developed to combat the new epidemic. For PARC to be efficacious and affordable, there was a clear need to have a vaccine that was thermostable. The need for a stable vaccine was underscored in politically unstable areas such as the Sudan, where the veterinary infrastructure has diminished and vaccination has been left in the hands of personnel who must act expeditiously. This paper reviews studies on various stabilizers and a modified lyophilization cycle that resulted in a highly thermostable RP vaccine. The useful shelf life of the vaccine, under African field conditions, was increased from less than one week to at least 100 days. For practical reasons, PARC recommends that the vaccine be used within 30 days of leaving refrigeration (the cold chain).