This is a phase Ib double-blind randomized placebo controlled age-deescalating trial to assess sagety and immunogenicity of two virosome formulated anti-malaria vaccine components (PEV 301 and PEV 302) administered in combination to healthy semi-immune Tanzanian adult and children.

Volunteers will be screened, enrolled, injected with the vaccine or comparator and followed by the clinicians at the Bagamoyo Research and Training Unit of the the Ifakara Health Research and Development Center (BRTU-IHRDC).

First, 10 adult males will be enrolled and randomized in 2 groups: Group AV (n=8) will be injected with the vaccine combination and group AP (n=2) will be vaccinated with the placebo=comparator (Inflexal V). 5 weeks later, 8 children will be enrolled first and randomized in 2 groups: Group CV (n=6) will be injected with the vaccine combination and group CP (n=2) will be vaccinated with comparator. 1 week later, the rest of the cohort (n=32) will be enrolled and randomized in 2 groups: Group CV (n=26) will be injected with the vaccine combination and group CP (n=6) will be vaccinated with comparator.

Immunogenicity assessments for humoral immune response will be made at baseline (days -10 to -2), day 30 (+4), day 90 (+4) (day of 2nd vaccination), 120 (+4), 180 (+7), and 365 (+14).

Cellular immune responses will be assessed before 1st vaccination (day 0), two weeks after 2nd vaccination (day 104 ±2), and one year after the 1st vaccination (day 365) Safety assessments will be made by the investigator at baseline (days -10 to -2, before the 1st immunization) and at day 1, 2, 3, 7, 14, 30 after each vaccination.

Inclusion Criteria:

1. Male volunteers aged between 18 and 45 years for the adult group, and children of both sexes aged 5-9 years for schoolchildren group
2. Written informed consent obtained from the volunteer (adult) or guardian/ legal representative (children). In case patient is illiterate, an impartial witness should be present during the entire consent procedure
3. Free of obvious health problems as established by medical history and clinical examination before entering the study
4. Body Mass Index between 18 and 30 for adults; MUAC less than 12 for children

Exclusion Criteria:

1. Use of any investigational or non-registered drug or vaccine within 30 days preceding the first dose of study vaccine, or planned use during the study period and safety follow-up
2. Chronic administration (defined as more than 14 days) of immunosuppressants or other immune-modifying drugs within six months prior to the first vaccine dose
3. Any chronic drug therapy to be continued during the study period
4. Any confirmed or suspected acquired immunosuppressive or immunodeficient condition, including human immunodeficiency virus (HIV) infection, or history of congenital or hereditary immunodeficiency
5. History of allergic disease or reactions likely to be exacerbated by any component of the vaccine
6. Acute disease at the time of enrollment. Acute disease is defined as the presence of a moderate or severe illness with or without fever (defined as temperature more than 37.5°C)
7. Acute or chronic, clinically significant pulmonary, cardiovascular, hepatic or renal functional abnormality, as determined by physical examination or laboratory screening tests
8. Acute or chronic diabetes
9. History of chronic alcohol consumption and/or intravenous drug abuse