The main reason for trial discontinuation was the inability to address the primary objectives of the study following an extended gap between the second and third doses.

USSPZV7 is a randomized, phase 1, double-blind, placebo-controlled trial of Sanaria® PfSPZ Vaccine administered on Days 1, 8 and 29 by direct venous inoculation (DVI) to assess safety, tolerability, immunogenicity, and vaccine efficacy (VE) against heterologous controlled human malaria infection (CHMI) with the 7G8 clone of Plasmodium falciparum (Pf) conducted at 3 or 12 weeks after the third immunization. The trial is designed to determine if individuals living in a non-malaria endemic area such as the United States (US) are protected against heterologous CHMI conducted at these time points.

1. Randomized, phase 1, double-blind, placebo-controlled clinical trial enrolling healthy adult participants 18-50-years-old living in the US.
2. The trial is designed to measure safety, tolerability, immunogenicity and VE against heterologous controlled human malaria vaccine conducted at 3 or 12 weeks after vaccination.
3. Participants will be randomized to two study groups, vaccine and placebo, in a 3:1 ratio. Treatment assignment will be double blind; however, whether a given participant will be receiving CHMI at 3 or 12 weeks will not be blind.
4. Bias will be minimized by the randomized, double-blind design and by the inability to distinguish vaccine or placebo based on appearance, tolerability or other characteristics discernable by clinical staff or study participants.
5. The study will take approximately 6 to 8 months to complete, not including 2-3 months of recruitment. The period of follow-up for each immunized participant and placebo controls is through 8 weeks post-CHMI.
6. Study participation by individuals will last 4 to 6 months (not including screening) depending upon group assignment.

Inclusion Criteria:

• Healthy adults (male or non-pregnant female) 18 to 50 years of age.
• Able and willing to participate for the duration of the study.
• Able and willing to provide written informed consent and satisfactorily complete a test of understanding with a passing score >80%.
• Physical examination and laboratory results without clinically significant findings.
• Women of childbearing potential must agree to use effective means of birth control (e.g. oral or implanted contraceptives, IUD, female condom, diaphragm with spermicide, cervical cap, abstinence, use of a condom by the sexual partner or sterile sexual partner) during the entire study. Women with a history of surgical or chemical sterilization (e.g. tubal ligation, hysterectomy, other).
• Willing to refrain from blood donation for 3 years following CHMI.
• Agree not to travel to a malaria endemic region during the trial.

Exclusion Criteria:

• Unable to provide informed consent including inability to pass the test of understanding, which is written in English for the US-based study sites.
• Receipt of a malaria vaccine in a prior clinical trial.
• History of a splenectomy or sickle cell disease.
• History of a neurologic disorder (including non-febrile seizures or complex febrile seizures) or formal history of migraine headache.
• Current use of systemic immunosuppressant pharmacotherapy.
• Receipt of a live vaccine within 4 weeks of first immunization or of 3 or more non-live vaccines within 2 weeks of first immunization.
• Women who are breast-feeding, pregnant or planning to become pregnant during the study period.
• Known allergy to atovaquone-proguanil (Malarone®), artemether-lumefantrine (Coartem®), or any component of the investigational products.
• A history of malaria in the 2 years prior to screening.
• Participation in any study involving investigational vaccine or drug within 4 weeks prior to enrollment that in the estimation of the site PI might adversely affect the individual's safety or the quality of data to be collected.
• Evidence of increased cardiovascular disease risk; defined as >10% five-year risk by nonlaboratory method.
• Plan to participate in another investigational vaccine/drug research during the study.
• Plan for major surgery between enrollment until 28 days post-CHMI.
• Use or planned use of any drug with anti-malarial activity that would precede or coincide with malaria challenge or vaccination.
• Anticipated use of medications known to cause drug reactions with atovaquone-proguanil or artemether-lumefantrine such as cimetidine, metoclopramide, antacids, and kaolin.
• Positive HBsAg or positive HIV or HCV testing consistent with active infection.
• An abnormal electrocardiogram, defined as one showing pathologic Q waves and significant STT wave changes; left ventricular hypertrophy; any non-sinus rhythm including isolated premature ventricular contractions, but excluding isolated premature atrial contractions; right or left bundle branch block; or advanced (secondary or tertiary) A-V heart block; or other clinically significant abnormalities on the electrocardiogram as determined by the consulting cardiologist.
• Any clinically significant deviation from the normal range in biochemistry or hematology tests measured at screening and not resolving.
• Any medical, psychiatric, social, behavioral or occupational condition or situation (including active alcohol or drug abuse) that, in the judgment of the site PI, impairs the volunteer's ability to give informed consent, increases the risk to the participant of participation in the study, affects the ability of the participant to participate fully in the study, or might negatively impact the quality, consistency, integrity or interpretation of data derived from their participation in the study.

Healthy adults (male or non-pregnant female).

Solicited local adverse events (AEs) were collected for two days after each immunization. Solicited systemic AEs were collected for 7 days after each immunization. Unsolicited AEs were collected from the first immunization to 28 days after the second immunization (since the study was terminated early). SAEs were to be recorded through the entire duration of the trial.

Solicited local AEs: pain & pruritus (by questioning participant), tenderness & induration (by palpation) & erythema, bruising & swelling (by visual inspection, swelling by viewing site laterally for swelling of skin). Solicited systemic AEs: fever (oral temp > 100.4 F), subjective fever, chills, headache, fatigue, malaise, myalgia, arthralgia, rigors, systemic allergic type reactions (rash, urticaria, pruritus, edema). Unsolicited AEs: open-ended question (e.g.do you have any other symptoms?).

The trial was terminated early. The main reason for trial discontinuation was the inability to address the primary objectives of the study following an extended gap between the second and third doses. Thus, vaccination was not completed and efficacy measurement was not performed.