The invention relates in various aspects to stem cells comprising a synthetic chimeric poxvirus (scPV), which can be used for the treatment of cancer or other infectious diseases. It also relates to methods for delivering the scPV comprising infecting the stem cells with the scPV and administering the infected stem cells to a subject.

The present disclosure provides methods for producing a vaccine composition containing a pathogen that is rendered noninfectious by exposure to hydrogen peroxide. The methods disclosed herein are suitable for the preparation of vaccines for a wide variety of pathogens, including viruses, bacteria and parasites. The disclosure also provides vaccine compositions (medicaments) containing a pathogen inactivated by exposure to hydrogen peroxide. Methods for eliciting an immune response in a subject by administering vaccine compositions containing a hydrogen peroxide inactivated pathogen are also provided.