From 1956 to ‘66 the incidence of SSPE in the northern half of the north island of N Zealand was approximately one hundred times greater than might be expected. No case was seen before 1956, and none has been since 1969. The incidence of the disease was greatest in the late 50s, then it waned and was associated with an increasing age at onset of symptoms. Mass vaccination of primary- school children with Salk vaccine (polio vaccine) was begun in 1956. The vaccine used is likely to have contained live SV4O virus. Killed measles virus is another possible contaminant. It is believe that the administration of Salk vaccine in N Zealand was related to the appearance of SSPE in the community. The idea that an unusual reaction to measles infection is the sole cause of SSPE is not consistent with the observations in N Zealand.

Source: Informed Parent  Issue 4, 2001