A Clinical Trial to Assess the Safety and Immunogenicity of New Malaria Vaccine Candidates ChAd63 Pfs25-IMX313 and MVA Pfs25-IMX313

Inclusion Criteria: The volunteer must satisfy all the following criteria to be eligible for the study: * Healthy adults aged 18 to 50 years * Able and willing (in the Investigator's opinion) to comply with all study requirements * Willing to allow the investigators to discuss the volunteer's medical history with their General Practitioner * For females only, willingness to practice continuous effective contraception (see below) during the study and a negative pregnancy test on the day(s) of screening and vaccination * Agreement to refrain from blood donation during the course of the study * Provide written informed consent Exclusion Criteria: The volunteer may not enter the study if any of the following apply: * Participation in another research study involving receipt of an investigational product in the 30 days preceding enrolment, or planned use during the study period * Prior receipt of an investigational malaria vaccine or any other investigational vaccine likely to impact on interpretation of the trial data. * Administration of immunoglobulins and/or any blood products within the three months preceding the planned administration of the vaccine candidate * Any confirmed or suspected immunosuppressive or immunodeficient state, including HIV infection; asplenia; recurrent, severe infections and chronic (more than 14 days) immunosuppressant medication within the past 6 months (inhaled and topical steroids are allowed) * History of allergic disease or reactions likely to be exacerbated by any component of the vaccine, e.g. egg products. * Any history of anaphylaxis in relation to vaccination * Pregnancy, lactation or willingness/intention to become pregnant during the study * History of cancer (except basal cell carcinoma of the skin and cervical carcinoma in situ) * History of serious psychiatric condition likely to affect participation in the study * Any other serious chronic illness requiring hospital specialist supervision * Suspected or known current alcohol abuse as defined by an alcohol intake of greater than 42 units every week * Suspected or known injecting drug abuse in the 5 years preceding enrolment * Seropositive for hepatitis B surface antigen (HBsAg) * Seropositive for hepatitis C virus (antibodies to HCV)