[Epidemic parotitis in Italy: results of a 1st vaccination trial]

Forty children over 12 months of age were inoculated subcutaneously with live mumps vaccine (Jeryl Lynn strain) and tested before and 6 weeks after vaccination for complement fixing, (CF) and hemadsorption neutralizing (HN) serum antibodies against a wild-mumps virus strain. CF antibody titers were not reliable for assessing both the previous immunity and the vaccine response. Among the 13 HN seronegative subjects the responders to the vaccine were 7, with a seroconversion rate of 53.8% and a geometric mean titer (GMT) of 1:2.6. Twenty (74.1%) of the 27 subjects already seropositive before the vaccination had a booster effect with an increase of the GMT from 1:8.29 to 1:33.89.