Adverse events following mumps vaccination
GACVS considered a comprehensive review of the world literature regarding the safety of mumps vaccination, with special attention being paid to the risk of vaccine-derived mumps meningitis. It was noted that higher rates of aseptic meningitis have been described for the Urabe, Leningrad–Zagreb and Leningrad-3 strain vaccines compared with the Jeryl–Lynn strain vaccine. The possible virological basis for this difference and/or the other characteristics of the product that might explain these differences are not known. Some of the variability observed in the risk of aseptic meningitis following use of the various mumps vaccine strains may reflect pre-existing immunity, in particular in older age groups, as well as the variable levels of sensitivity of surveillance and of diagnostic practices in different settings. A detailed final report of this review, in which the estimate of risks will be assessed, will be published in due course. GACVS concluded that risk estimates vary between studies, reflecting differences in study settings and circumstances and in degrees of surveillance. The available data are insufficient to distinguish between the safety profile with regard to aseptic meningitis for Urabe, Leningrad–Zagreb and Leningrad-3 strains. The Committee is not aware of any cases of virologically proven aseptic meningitis following Jeryl–Lynn vaccine. If Urabe, Leningrad–Zagreb and Leningrad-3 strain vaccines are being used in mass vaccination campaigns, national immunization programmes need to take into account the potential for clustering of aseptic meningitis following the campaigns. The Committee noted that, until now, all reported cases of vaccinederived mumps meningitis have recovered. There is no known case with long-term sequelae. GACVS further considered a proposal for a mumps vaccine virus strain bank, to be developed at the invitation of WHO, which has considerable potential scientific interest. WHO will give further attention to the possibility of such a strain bank being established.