Discloses the use of a replication incompetent poxvirus for the preparation of an immunogenic composition comprising the said replication incompetent poxvirus for inducing an immune response against a replication competent poxvirus in a human. The immunogenic composition is adapted to be administered to the human between 0 and 48 hours after infection with the replication competent poxvirus. The replication incompetent poxvirus is Modified Vaccinia Virus Ankara (MVA) which may be modified to comprise an epitope of a replication competent poxvirus. Further discloses dosage levels of the MVA in the immunogenic composition. The composition finds therapeutic application in immediate and safe treatment of poxvirus-type infections and the inherent ability of the vaccine to provide cross reactive protection against poxvirus-type infections.
