Subacute sclerosing panencephalitis and measles vaccination
The WHO Regional Office for Europe requested GACVS to review the risk of measles vaccine strains causing subacute sclerosing panencephalitis (SSPE). The United States Institute of Medicine (IOM) statements in its 1994 and 2001 reviews refer to absent or inadequate evidence either to reject or accept any causal relationship between measles-containing vaccines and SSPE in immunocompetent individuals. It is uncertain whether there is enough evidence from viral RNA sequencing and classification to warrant any modification of the IOM conclusions. However, GACVS noted that: (i) all reports published since the IOM review in 2001 containing information on measles virus classification in SSPE-immunocompetent patients indicate the presence of wild (not vaccine) measles strains; and (ii) in countries where measles has been controlled, SSPE has either declined substantially or no longer occurs. These findings do not suggest an association between measles vaccines and SSPE. GACVS will commission a review of the epidemiology of SSPE in relation to measles vaccine, the results of which will be considered at its December 2005 meeting.