The present invention provides a composition comprising a first antibody molecule that specifically recognises CD3 and a second antibody molecule that specifically recognises CD7, for use in a method of treatment, or preventative treatment, of viral infection or viral reactivation in a mammalian subject undergoing immunomodulatory treatment, wherein the first and second antibody molecules are each provided with a toxic moiety. Also provided is a method of treating a mammalian subject having, or being at risk of developing, chronic Graft versus Host disease (cGVHD). Also provided is a related pharmaceutical composition.