Global Advisory Committee on Vaccine Safety
The SA 14-14-2 live attenuated JE vaccine, produced by the Chengdu Institute of Biological Products, has been used on a large scale in China since 1988, and more recently has been being exported to several countries in the region. The uptake of this vaccine has increased substantially, and it is now the most widely used JE vaccine.
GACVS has reviewed safety aspects of this vaccine at two of its meetings (twelfth, held on 9-10 June 2005, and fifteenth, held on 29-30 November 2006). GACVS reviewed data related to the safety, immunogenicity and efficacy of the vaccine, and scrutinized data on co-administration with measles vaccine.
GACVS concluded that the short-term safety profile of live JE vaccine appears satisfactory and that there appears to be a high level of vaccine efficacy after the administration of a single dose. The vaccine is immunogenic in infants from the age of eight months of age, and can be safely administered with measles vaccine from nine months. However, a modest reduction in both seroconversion and GMT titre has been observed for measles vaccine when co-administered with JE vaccine. Current data suggest, however, that the interference is only temporary, and co-administration of live JE vaccine and measles vaccine is acceptable. Further studies to confirm that measles vaccine effectiveness remains undiminished were encouraged.
In relation to serious adverse events reported after mass vaccination campaigns in India during 2006, no direct causality has been established between the reported illnesses and the SA14-14-2 JE vaccine.
Nevertheless, GACVS recommended that in future, potential vaccine-related serious adverse events should be better investigated. Furthermore, more investigations are required to assess the possible risk of low frequency adverse events (especially neurological). Since live JE vaccine is currently used in “catch-up” campaigns on many millions of children in Asian countries, the opportunity should be taken to examine whether the vaccine safety profile remains valid in large study populations.