Study on stability of live attenuated yellow fever vaccine in China / 中华实验和临床病毒学杂志

ABSTRACT

Objective@#To study the viral titers of live attenuated yellow fever vaccine in China under different storage conditions and time, and to provide data to support the stability of the vaccine.@*Methods@#The viral titers of live attenuated yellow fever vaccines stored at different time points at -20 ℃, 4 ℃, 25 ℃ and 37 ℃ were determined; the viral titers of vaccines stored at different time points at the viral titers of vaccines expired for different time points were determined; the viral titers of vaccines were determined after storing at -20 ℃ after being taken away from the cold-chain during transportation; the titer of the virus was determined at different time points after thawing.@*Results@#The viral titer of the live attenuated yellow fever vaccine stored at -20 ℃ for 24 months (validity period) decreased only by 0.4-0.5 LgPFU/ml; the viral titer decreased by 0.7 LgPFU/ml, 1.0-1.4 LgPFU/ml and 2.3-2.6 LgPFU/ml respectively when the vaccine was stored at 4 ℃, 25 ℃ and 37 ℃ for 8weeks. The viral titers decreased by 0.4-0.6 LgPFU/ml, 0.6-0.7 LgPFU/ml, 0.6-0.7 LgPFU/ml and 0.9 LgPFU/ml respectively 8 months 10 months, 44 months and 76 months after the expiration date. The titer of the virus decreased slightly from 0 to 0.2 LgPFU/ml when the vaccine was stored at 4 ℃ for 2 h, 25 ℃ for 2 h, 37 ℃ for 2 h, then -20 ℃ for 2 weeks. Afterthawing, the titers of virus decreased by 0.1-0.4 LgPFU/ml at room temperature for 120 minutes.@*Conclusions@#The live attenuated yellow fever vaccine in China has good stability and is very stable at the current standard storage temperature -20 ℃. Short time exposure to high temperature, whether in lyophilized state or after being thawed, the viral titer of vaccine remained almost unchanged.