Safety and Immunogenicity of Pfs25M-EPA/AS01 and Pfs230D1M-EPA/AS01 Vaccines, Transmission Blocking Vaccines Against Plasmodium Falciparum, at Full and Fractional Dosing in Adults in Mali

Background: Researchers are looking for new ways to control and eradicate malaria. They want to test vaccines to block malaria transmission in adults in Mali. These vaccines work by inducing antibodies in a person. The antibody is then taken up with blood by a mosquito that bites the person. This blocks parasite development in the mosquito. This stops malaria transmission to another person. Objective: To test the safety, reactogenicity, immunogenicity, and transmission-blocking activity of the vaccines Pfs25M-EPA and Pfs230D1M-EPA with AS01 in Malian adults. Eligibility: Healthy Malians ages 18-50 living in certain areas in Mali who: Are not pregnant or breastfeeding Are not infected with HIV, Hepatitis B and Hepatitis C Do not have evidence of immunodeficiency Do not have history of severe allergic reaction or anaphylaxis Design: Participants will be screened with: Medical history Physical exam Malaria Comprehension Exam Blood and urine tests Electrocardiogram (for participants in certain study groups) Participants will be randomly assigned to a study group. Participants will be monitored for 12-16 months. For the first 7 months, they will have between 1 and nine visits a month. The number depends on the month and on what group they are in. For the rest of the months, they will have 1 monthly visit. Each visit includes a physical exam. Most include blood tests. Participants will get 3 doses of a study or comparator vaccine. They get the vaccine through an injection in the upper arm. This occurs at their first visit, then 1 month later, and then 5 months later. Participants will be followed for at least 6 months after the last vaccine. If participants develop an injection site rash or reaction, photographs may be taken of the site.