Described is a composition and method for reducing the occurrence and severity of infectious diseases, especially infectious diseases such as SARS, in which lipid-containing infectious viral organisms are found in biological fluids, such as blood. The present invention employs solvents useful for extracting lipids from the lipid-containing infectious viral organism thereby creating immunogenic modified, partially delipidated viral particles with reduced infectivity. The present invention provides delipidated viral vaccine compositions, such as therapeutic vaccine compositions, comprising these modified, partially delipidated viral particles with reduced infectivity, optionally combined with a pharmaceutically acceptable carrier or an immunostimulant. The vaccine composition is administered to a patient to provide protection against the lipid-containing infectious viral organism or, in case of a therapeutic vaccine, to treat or alleviate infection against the lipid-containing infections viral organism. The vaccine compositions of the present invention include combination vaccines of modified viral particles obtained from one or more strains of a virus and/or one or more types of virus.
