Sporozoite immunization: innovative translational science to support the fight against malaria

Figures & data

Figure 1. Malaria sporozoite. Scanning electron micrograph of a Plasmodium cynomolgi sporozoite superimposed on a scanning electron micrograph of a rat liver sinusoid. P. falciparum sporozoites are similar in appearance and are typically 8–10 microns in length. They are large eukaryotic cells able to glide along the endothelium, traverse interstitial spaces, and penetrate Kupffer cells and hepatocytes. Pc = parenchymal cell (hepatocyte); fsc = fat-storing cells (stellate cell); SD = space of Disse. Arrows point to endothelial cell fenestrations. This composite image was made by Ute Frevert, who modified the shape of the sporozoite to better reflect the ability of the parasite to flex when gliding along natural tissue structures as shown by intravital cinematography. Reproduced with permission from Comparative Hepatology (no changes were made) [86].

Figure 2. PfSPZ platform technologies. (a) Illustration of a liver sinusoid showing the invading sporozoites (green progressing to red as they replicate and differentiate). H = hepatocyte, KC = Kupffer cell, EC = endothelial cell. Reproduced from Nature [8] with permission. Design credit: Sumana Chakravarty. (b) radiation-attenuated and first-generation genetically attenuated (GA) PfSPZ invade hepatocytes and partially develop, but do not replicate. Infectious PfSPZ in PfSPZ-CVac invade hepatocytes and partially develop if a liver-active antimalarial is administered (e.g. pyrimethamine, azithromycin) or fully develop including normal replication (releasing merozoites into the blood stream) if a blood-stage active antimalarial is administered (e.g. chloroquine). The extent of development therefore depends on which drug is used and when it is administered. Second-generation GA parasites have a late-arresting phenotype and halt development before the release of merozoites. Potency appears to increase with further development, whereas safety concerns arise should the parasite release merozoites into the blood.

Table 1. Key milestones and innovations

Key milestones and innovations relating to aseptic, purified whole PfSPZ		Date*	Trial Registry	Publications
First manufacture of GMP compliant, aseptic purified, cryopreserved PfSPZ	Sanaria Inc., U.S.A.	May 2008	Not applicable	[88]
First clinical testing of PfSPZ Vaccine (ID and SC routes)	Naval Medical Research Center, U.S.A.; University of Maryland Center for Vaccine Development, U.S.A.	May 2009	NCT01001650	[51]
First clinical testing of PfSPZ Challenge (ID route)	Radboud University Medical Center, The Netherlands	Oct 2010	NCT01086917	[113]
First intravenous administration of PfSPZ Vaccine in humans and first demonstration of short term (3 weeks) 100% vaccine efficacy (VE) against homologous CHMI	Vaccine Research Center, NIAID, U.S.A.	Oct 2011	NCT01441167	[1]
First clinical testing of PfSPZ Challenge in Africa (ID route)	Ifakara Health Institute, Tanzania	Feb 2012	NCT01540903	[119]
First intravenous administration of PfSPZ Challenge in humans	University of Tübingen Institute for Tropical Medicine, Germany; Barcelona Center for International Health Research (CRESIB) Hospital Clinic, Spain	Jun 2012	NCT01624961 and NCT01771848	[114]
First clinical testing of PfSPZ-CVac (ID route)	Radboud University Medical Center, The Netherlands	Sep 2012	NCT01728701	[122]
First use of PfSPZ Challenge to study naturally acquired immunity	Lambaréné Centre for Medical Research (CERMEL), Gabon; University of Tübingen Institute for Tropical Medicine, Germany	Dec 2013	NCT02237586	[132]
First testing of PfSPZ Vaccine in Africa	Malaria Research & Training Center, University of Bamako, Mali; NIH Laboratory of Malaria Immunology and Vaccinology, U.S.A.	Jan 2014	NCT01988636	[65]
First use of CHMI to test vaccine efficacy in Africa	Ifakara Health Institute, Tanzania	Nov 2014	NCT02132299	[124]
First intravenous administration of PfSPZ-CVac in humans and first demonstration of medium term (10 weeks) 100% vaccine efficacy (VE) against homologous CHMI	University of Tübingen Institute for Tropical Medicine, Germany	Apr 2014 Nov 2014	NCT02115516	[8]
First pediatric testing of PfSPZ Vaccine	Ifakara Health Institute, Tanzania	Jan 2016	NCT02613520	[136]
First comparison of inoculation of PfSPZ via PfSPZ Challenge vs. mosquito bites	Seattle Malaria Clinical Trials Center, U.S.A.	Mar 2016	NCT02562872	[131]
First testing of multidose priming of PfSPZ Vaccine	University of Maryland, U.S.A.	Jul 2016	NCT02601716	[163]
First testing of condensed regimens of PfSPZ Vaccine	University of Tübingen, Germany	Sep 2016	NCT02704533	[6]
First head-to-head comparison of PfSPZ Vaccine and PfSPZ-CVac	Equatorial Guinea Malaria Vaccine Initiative, Equatorial Guinea; Ifakara Health Institute, Tanzania	Nov 2016	NCT02859350	[126]Jongo, in press, American Journal of Tropical Medicine and Hygiene
First pediatric testing for field efficacy	Kenya Medical Research Institute, Kisumu, Kenya; Centers for Disease Control, U.S.A.; Vaccine Research Center, NIAID, U.S.A.; Liverpool School of Tropical Medicine, UK	Jan 2017	NCT02687373	[164]
First testing of genetically attenuated injectable PfSPZ	Leiden University Medical Center, The Netherlands; Radboud University Medical Center, The Netherlands	May 2017	NCT0316121	[146]
First demonstration of 18-month protection against Pf infection in the field (PfSPZ Vaccine)	National Center for Malaria Research and Training, Burkina Faso; University of Maryland Center for Vaccine Development, U.S.A.	Feb 2018	NCT02663700	[7]
First testing of PfSPZ Vaccine in immunocompromised individuals (HIV+)	Ifakara Health Institute, Tanzania	Feb 2018	NCT03420053	Jongo, in press, Journal of Clinical Investigation.
First demonstration of medium term (12 weeks) 100% vaccine efficacy (VE) against heterologous CHMI (PfSPZ-CVac)	NIH Laboratory of Malaria Immunology and Vaccinology, U.S.A.	Feb 2019	NCT03083847	[68]
First demonstration of 18-month protection against Pf clinical malaria in the field and of protection against Pf infection during pregnancy (PfSPZ Vaccine).	Malaria Research & Training Center, University of Bamako, Mali; NIH Laboratory of Malaria Immunology and Vaccinology, U.S.A.	Feb 2021	NCT03989102	unpublished
First testing of PfSPZ Vaccine and PfSPZ-CVac in travelers to endemic areas	Faculty of Medicine, University of Indonesia, Jakarta, Indonesia; Oxford University Clinical Research Unit, Jakarta (OUCRU, Jakarta), Indonesia; Health Research Center, Army of the Republic of Indonesia, Jakarta, Indonesia; Eijkman Center for Molecular Biology, National Research and Innovation Agency, Jakarta, Indonesia	May 2022	NCT03503058	unpublished
Anticipated future firsts
First testing of PfSPZ Vaccine in pregnant women	Malaria Research and Training Center, University of Bamako; NIH Laboratory of Malaria Immunology and Vaccinology
First testing of injectable genetically attenuated late liver stage-arresting replication competent (LARC) parasites, PfSPZ-LARC2 Vaccine in malaria-naive individuals	University of Tübingen Institute for Tropical Medicine; Center for Global Infectious Disease Research, Seattle Children’s Research Institute & University of Washington
First testing of genetically attenuated parasites in Africa, PfSPZ-LARC2 Vaccine	Groupe de Recherche Action en Santé (GRAS), Burkina Faso; University of Maryland Center for Vaccine Development, U.S.A.

*Firsts related to first clinical testing are referenced by the date of the first vaccine dose; firsts related to protection are referenced by the date CHMI follow-up or field surveillance follow-up ended.

Figure 4. Protective efficacy of PfSPZ Vaccine against naturally transmitted Pf infection in Malian adults (MLSPZV1 clinical trial). Vaccine efficacy was analyzed by time to first positive blood smear, with day 0 at 28 days after the fifth vaccination. The inverse survival curves include participants who received all five vaccinations and were evaluable for the primary exploratory efficacy endpoint. Five participants (one in the PfSPZ Vaccine group and four in the placebo group) were censored from the primary efficacy analysis because they had a positive blood smear before 28 days after the fifth vaccination. PfSPZ=Plasmodium falciparum sporozoite. Reproduced with permission from the Lancet ID (no changes were made) [3].

Figure 5. Differential antibody and T-cell responses to PfSPZ Vaccine by age in Tanzanian adults, adolescents, children, and infants. Panel a. Antibody levels to Pf circumsporozoite protein as measured by enzyme-linked immunosorbent assay (difference between two-weeks-post-immunization and pre-immunization) after immunizing 18–45-year-olds, 11–17-year-olds, 6–10-year-olds, 1–5-year-olds, and 6–11-month-olds with three doses of 9.0x10⁵ PfSPZ of PfSPZ Vaccine at eight-week intervals. VRC314, an earlier trial in which malaria-naive US adults were immunized with the same dosage regimen and antibody levels were assessed using the same PfCSP ELISA conducted in the same laboratory, is shown as a comparison (for VRC314, filled in circles indicate volunteers protected against CHMI, empty circles the unprotected volunteers). Medians with interquartile ranges are shown. Panel b. PfSPZ-specific memory CD4 T-cell responses pre- and post-vaccination after incubation with PfSPZ, expressed as the percent of cells in the blood expressing interferon gamma (IFN-γ), interleukin 2 (IL-2), or tumor necrosis factor alpha (TNF-α) at pre-immunization or 2 weeks after the first and third doses of PfSPZ Vaccine (9.0×10⁵). VRC314 data (malaria-naive adults) are included as a comparison. Reproduced with permission from the American journal of Tropical Medicine and Hygiene (no changes were made) [136].

Figure 6. Parasitemia detected by qPCR after the first, second and third dose of 2×10⁵ PfSPZ for PfSPZ-CVac (CQ) and PfSPZ-CVac (PYR). Median parasitaemia values and interquartile ranges are shown for positive PfSPZ-CVac (CQ) participants (no PfSPZ-CVac (PYR) participants were positive, since pyrimethamine kills the parasites during liver stage development). Dose 1, PfSPZ Challenge inoculation under CQ or PYR treatment cover with follow-up for 14 days; doses 2 and 3, PfSPZ Challenge inoculation under CQ or PYR treatment cover with follow-up for 10 days. The table shows (from left to right in each cell): the number of participants who were positive by qPCR/the number of injected participants; the median peak parasite density of positive participants (parasites per ml); and the mean day of peak parasite density (positive participants). Six PfSPZ-CVac (CQ) recipients went on to heterologous CHMI and 6/6 (100%) were protected; nine PfSPZ-CVac (PYR) recipients went on to heterologous CHMI and 7/9 (78%) were protected. ND, not detected; n/a, not applicable. Reproduced with permission from Nature (no changes were made) [68].

Figure 7. Parasite density estimated by qRT-PCR in participants in a PfSPZ-CVac (CQ) trial conducted at the Kaiser Permanente Washington Health Research Institute, Seattle. (A) Triangle symbols indicate the first, second, and third days of vaccine administration. The numbers above each peak of parasitemia display the number of persons positive with transient parasitemia divided by the total number of vaccine recipients for that dose of vaccine. Days are listed relative to the first dose of vaccine. Group 1 received a PfSPZ Challenge dose of 5.12x10⁴ PfSPZ for each of three doses administered by DVI seven days apart. Group 3 received a PfSPZ Challenge dose of 1.024x10⁵ PfSPZ for each of three doses administered by DVI five days apart. All participants underwent CHMI 10 weeks after the last vaccine dose. 7/7 participants became infected in group 1 (vaccine efficacy 0%) while only 2/8 participants became infected in group 3 (vaccine efficacy 75%). It is notable that administration of PfSPZ-CVac on a schedule where vaccine administrations #2 and #3 coincided with sub-microscopic blood-stage parasitemia (group 1) was associated with an absence of sterile protective immunity, whereas dodging parasitemia (group 3) appeared to restore the expected protective efficacy. Reproduced with permission from PLoS pathogens (no changes were made) [127].

Figure 3. The International PfSPZ Consortium. Seattle Children’s Research Institute hosted 289 researchers from 86 institutions from 28 countries in person and virtually at the International Plasmodium falciparum Consortium (i-PfSPZ-C) meeting held November 3–4, 2022, to present data and set research and clinical development strategies for PfSPZ-based vaccines and products.

Figure 8. Target populations for PfSPZ vaccines. The objective for PfSPZ vaccine development is high-level prevention of Pf infection. Major risk groups potentially benefiting from such a vaccine are listed. It is anticipated that licensure will occur first in the EU with an indication to prevent malaria in travelers (including travelers who travel within their own country from areas without malaria to areas with malaria), with licensure in the U.S.A. and malaria-endemic areas thereafter. Major risk groups are identified. The ultimate objective is use in MVPs to achieve focal and regional elimination.

Figure 9. A hypothetical mass vaccination program (MVP) using PfSPZ-LARC2 Vaccine. As envisioned by the authors, a malaria elimination campaign would be designed for a target geographical region including appropriate community engagement. Mass drug administration (MDA) such as artesunate + pyronaridine [290] would be conducted prior to immunization to reduce the suppression of vaccine responses by existing parasitemia and to eliminate the human parasite reservoir. Intensified vector control would help to eliminate the mosquito reservoir. Immunization with PfSPZ-LARC2 Vaccine would then be performed to protect the population against the acquisition of new infections. An additional round of MDA might be needed post immunization to achieve elimination. Primaquine would be used to eliminate infectious gametocytes. AS = artesunate; PYRON = pyronaridine; PQ = primaquine.

Figure 10. Efficacy of PfSPZ Vaccine against naturally transmitted Pf infection in Burkina Faso adults. Inverse survival curves for time after the last vaccination to first positive thick blood smear (asymptomatic + symptomatic infection) are shown. Efficacy was analyzed as 1-hazard ratio for the primary follow-up period (0–24 weeks post third vaccination) and the extended follow-up period (0–76 weeks post third vaccination). The survival curves include 79 participants who received all three vaccinations and were evaluable for the vaccine efficacy endpoint. Reproduced with permission from Science Translational Medicine (no significant changes were made) [7].

Table

Study Identifier (Clinicaltrials.gov)Start Date	Study Design Summary	PfSPZ Immunization Schedules Evaluated (Dose, Route, Number of administrations)	Numbers of Volunteers Receiving Vaccine	Reference
1. NMRC/UMB CVD (NCT01001650) May 2009 (completed)	Phase 1, open-label, dose-escalation with CHMI in U.S.A. (ID, SC only)	7.5×10^3 SC x 4; 7.5 × 10^3 ID x 4; 3×10^4 SC x 4; 3 × 10^4 ID x 4; 1.35×10^5 SC x 4 or 6; 1.35 × 10^5 ID x 4 or 6	Malaria-naïve adults: 80	[51]
2. VRC 312 (NCT01441167) Oct 2011 (completed)	Phase 1, open-label, dose-escalation with CHMI in U.S.A. (IV only)	2×10^3 IV x 2; 7.5 × 10^3 IV x 4 or 6; 3×10^5 IV x 4 or 6; 1.35 × 10^5 IV x 4 or 5	Malaria-naïve adults: 40	[1]
3. VRC 314 (NCT02015091) Dec 2013 (completed)	Phase 1, open-label, dose-escalation, regimen comparison with CHMI in U.S.A. (IV or IM)	2.2×10^6 IM x 4; 1.35×10^5 IV x 4 + 4.5×10^5 IV boost; 2.7×10^5 IV x 3 or 4; 2.7×10^5 IV x 2 + 4.5×10^5 IV x 2; 9.0×10^5 IV x 3	Malaria-naïve adults: 93	[4,5]
Administration in all following trials by DVI only
4. Mali 1 (NCT01988636) Jan 2014 (completed)	Phase 1, randomized, double-blind placebo-controlled* field efficacy in Mali	1.35×10^5 x 1 + 2.7×10^5 x 1; 2.7×10^5 x 5	Malaria-exposed adults: 58	[65]
5. BSPZV1 (NCT02132299) May 2014 (completed)	Phase 1, randomized, double- blind placebo-controlled* with CHMI (by needle and syringe) in Tanzania	3×10^4 x 1, then 1.35 × 10^5 x 1, then 2.7 × 10^5 x 1; 1.35×10^5 x 5; 2.7×10^5 x 5	Malaria-exposed adults: 49	[124]
6. WRAIR 2080 (NCT02215707) Jun 2014 (completed)	Phase 1, open-label, regimen comparison with CHMI in U.S.A.	2.7×10^5 x 5; 4.5×10^5 x 3	Malaria-naïve adults: 45	[187]
7. EGSPZV1 (NCT02418962) Mar 2015 (completed)	Phase 1, open-label, dose-escalation in Equatorial Guinea	1.35×10^5 x 1; then 2.7 × 10^5 x 1; 2.7×10^5 x 3	Malaria-exposed adults: 23	[162]
8. BSPZV2 (NCT02613520) Dec 2015 (completed)	Phase 1 dose escalation, double-blind, randomized, placebo-controlled* with CHMI (by needle and syringe) in Tanzania	Adults, older children: 9 × 10^5 x 3; 1.8 × 10^6 x 3; Younger children: 4.5 × 10^5 x 3; 9 × 10^6 x 3 Infants : 2.7 × 10^5 x 1; 4.5 × 10^5 x 3; 9 × 10^6 x 3	Malaria-exposed adults: 12 children: 36 infants: 15	[2,136]
9. Mali 2 (NCT02627456) Jan 2016 (completed)	Phase 1 dose escalation with CHMI followed by Phase 2 randomized, double-blind, placebo-controlled* field efficacy in Mali	Ph 1: 4.5 × 10^5 x 1; then 9 × 10^5 x 1; then 1.8 × 10^6 x 3; Ph 2: 1.8 × 10^6 x 3	Malaria-exposed adults: 100	[3]
10. Burkina Faso 1 (NCT02663700) Apr 2016 (completed)	Phase 1 dose escalation followed by Phase 2, randomized, double-blind placebo-controlled* field efficacy in Burkina Faso	Ph 1: 4.5 × 10^5 x 2; 9 × 10^5 x 2; 1.8 × 10^6 x 2; 2.7 × 10^6 x 2 Ph 2: 2.7 × 10^6 x 3	Malaria-exposed adults: 71	[7]
11. Warfighter 2 (NCT02601716) Apr 2016 (completed)	Phase 2, open-label, regimen comparison with CHMI in U.S.A.	4.5×10^5 x 5 (Days 1, 3, 5, 7 and week 16); 9 × 10^5 x 3 (Weeks 1, 9, 17); 1.8 × 10^6 x 3 (Weeks 1, 9, 17); 2.7 × 10^6 x 1 + 9×10^5 x 2 (Weeks 1, 9, 17)	Malaria-naive adults: 60	[163]
12. KSZPV1 (NCT02687373) Jul 2016 (completed)	Phase 1 dose escalation followed by Phase 2 double-blind, randomized, placebo-controlled* with field efficacy in Kenya	Ph 1 - Older children: 4.5 × 10^5 x 1; 9 × 10^5 x 2; 1.8 × 10^6 x 2 Ph 1 - Younger children, infants: 1.35 × 10^5 x 1; 2.7 × 10^5 x 1; 4.5 × 10^5 x 1; 9 × 10^5 x 2; 1.8 × 10^6 x 2; Ph 2 - Infants: 4.5 × 10^5, 9 × 10^5, or 1.8 × 10^6, all x 3 (Weeks 1, 9, 17)	Malaria-exposed children: 64 infants: 352	[138,139,164]
13. MAVACHE (NCT02704533) Sep 2016 (completed)	Phase 1 dose escalation, regimen-condensation and dose number reduction with CHMI in Germany	Dose selection: 9 × 10^5 x 3 (Days 1, 8, 29); 1.8 × 10^6 x 2 (Days 1, 8); 2.7 × 10^6 x 2 (Days 1, 8); Verification: 9 × 10^5 x 3 (Days 1, 8, 29)	Malaria-naive adults: 42	[6]
14. EGSPZV2 (NCT02859350) Nov 2016 (completed)	Phase 1 dose escalation, randomized double-blind, placebo-controlled* with head-to-head PfSPZ Vaccine and PfSPZ-CVac comparison in Equatorial Guinea	Adults (PfSPZ Vaccine): 2.7 × 10^6 x 3 (weeks 1, 9, 17) Adults (PfSPZ-CVac): 1 × 10^5 x 3 (weeks 1, 5, 9) Children, infants (PfSPZ Vaccine): 1.8 × 10^6 x 3 (weeks 1, 9, 17)	PfSPZ Vaccine: Malaria-exposed adults: 32; children: 36; infants: 15 PfSPZ-CVac: Malaria-exposed adults: 20**	[126] Jongo, in press, American Journal of Tropical Medicine and Hygiene
15. PfSPZ-GA1 (NCT03163121) May 2017 (completed)	Phase 1 dose escalation, randomized double-blind, placebo-controlled* with head-to-head PfSPZ-GA1 and PfSPZ Vaccine comparison in The Netherlands	PfSPZ-GA1: 1.35 × 10^5 x 1; 4.5 × 10^5 x 1; 9.0 × 10^5 x 1; 4.5 × 10^5 x 3; 9.0 × 10^5 x 3 (Weeks 1, 9, 17) PfSPZ Vaccine: 4.5 × 10^5 x 3 (Weeks 1, 9, 17)	Malaria-naive adults: 58***	[146]
16. BSPZV3a (NCT03420053) Feb 2018 (completed)	Phase 1 dose escalation, randomized double-blind, placebo-controlled* with CHMI in Tanzania	4.5×10^5 x 5 (Days 1, 3, 5, 7 and 29); or 9 × 10^5 x 5 (Days 1, 3, 5, 7 and 29)	Malaria-exposed HIV- and HIV+ adults: 21	Jongo, in press, Journal of Clinical Investigation
17. MSPZV3 (NCT03510481) Jun 2018 (completed)	Phase 2 double-blind, randomized, placebo-controlled* with field efficacy in Mali	9×10^5 x 3 (Days 1, 8 and 29); or 9 × 10^5 x 3 (Weeks 1, 9, 17)	Malaria-exposed adults: 210	Diawara & Healy, unpublished
18. LaSPZV1 (NCT03521973) Jun 2018 (ongoing)	Phase 2 double-blind, randomized, placebo-controlled* with field efficacy in Gabon	9×10^5 x 3 (Days 1, 8 and 29)	Malaria-exposed children: 200	Agnandji, unpublished
19. EGSPZV3 (NCT03590340) Aug 2018 (completed)	Phase 1 double-blind, randomized, placebo-controlled* with CHMI in Equatorial Guinea	9×10^5 x 3 (Days 1, 8 and 29); 9 × 10^5 x 5 (Days 1, 3, 5, 7 and 29); 9 × 10^5 x 5 (Days 1, 3, 5, 7 and Week 17); 9 × 10^5 x 4 (Days 1, 3, 5, 7)	Malaria-exposed adults: 104	[129]
20. MSPZV4 (NCT03510481) July 2019 (ongoing)	Phase 2 double-blind, randomized, placebo-controlled* with field efficacy in Mali	9×10^5 x 3 (Days 1, 8 and 29); 1.8 × 10^6 x 3 (Days 1, 8 and 29)	Malaria-exposed women of child-bearing potential: 300	Diawara & Healy, unpublished
21. Warfighter 3 (NCT04966871) Oct 2021 (completed)	Phase 1 double-blind, randomized, placebo-controlled* with heterologous CHMI in U.S.A.	9×10^5 x 3 (Days 1, 8 and 29)	Malaria-naive adults: 42	Kublin, unpublished
22. IDSPZV1 (NCT03503058) June 2022 (ongoing)	Phase 2, randomized, double-blind placebo-controlled* field efficacy in Indonesia	9 × 10^5 (Days 1, 8 and 29)	Malaria-naive adults: 124	Nelwan, unpublished
23. Warfighter 3 (NCT05604521) Oct 2022 (ongoing)	Phase 1 double-blind, randomized, placebo-controlled* with heterologous CHMI in U.S.A.	9×10^5 x 3 (Days 1, 8 and 29)	Malaria-naive adults: 45	Lyke, unpublished
*The placebo control used in all trials is normal saline; ** 20/52 adult volunteers in EGSPZV2 received PfSPZ-CVac; *** 45/58 adults volunteers in PfSPZ-GA1 received PfSPZ-GA1; ‘then’ means same research subjects then received an additional different-sized dose.
In these trials, dosing schedules have evaluated various intervals between immunizations ranging from 4 to 16 weeks.

Table

Study Identifier(Clinicaltrials.gov)Start Date	Study Design Summary	Partner drug	PfSPZ Immunization Schedules Evaluated (Dose, Route, Number of administrations)	Numbers of Volunteers Receiving Vaccine	Reference
1. TIP-5 (NCT01728701) Sep 2012 (completed)	Phase 1 randomized double-blind, placebo-controlled* with CHMI in The Netherlands	CQ	7.5 × 10^4 ID x 3 (weeks 1, 5, 9) 7.5 × 10^4 ID x 4 (weeks 1, 5, 9, 33)	Malaria-naive adults: 20	[122]
Administration in all following trials by DVI only
2. TÜCHMI-002 (NCT02115516) Apr 2014 (completed)	Phase 1 dose escalation, regimen condensation with CHMI in Germany	CQ CQ + azithromycin	3.2×10^3 x 3; 1.28 × 10^4 x 3; 5.12 × 10^4 x 3 (Weeks 1, 5, 9); 5.12 × 10^4 x 3 (Weeks 1, 3, 5); 5.12 × 10^4 x 3 (Days 1, 6, 11)	Malaria-naive adults: 45	[8]
3. 15-I-0169 (NCT02511054) Nov 2015 (completed)	Phase 1 regimen comparison with CHMI in U.S.A.	CQ CQ + pyrimethamine	5.12 × 10^4 x 3 (Weeks 1, 5, 9)	Malaria-naive adults: 20	[68]
4. MALACHITE (NCT02858817) Nov 2016 (completed)	Phase 1 dose escalation with CHMI in Germany	Atovaquone + proguanil	5.12×10^4 x 3 (Weeks 1, 5, 9); 1.5 × 10^5 x 3 (Weeks 1, 5, 9)	Malaria-naive adults: 21	[168]
5. EGSPZV2 (NCT02859350) Jan 2017 (completed)	Phase 1 randomized double-blind, placebo-controlled* with CHMI and head-to-head comparison of PfSPZ Vaccine and PfSPZ-CVac in Equatorial Guinea	CQ	Adults (PfSPZ Vaccine): 2.7 × 10^6 x 3 (weeks 1, 9, 17) Adults (PfSPZ-CVac): 1 × 10^5 x 3 (weeks 1, 5, 9) Children, infants (PfSPZ Vaccine): 1.8 × 10^6 x 3 (weeks 1, 9, 17)	PfSPZ Vaccine: Malaria-exposed adults: 32; children: 36; infants: 15 PfSPZ-CVac: Malaria-exposed adults: 20	[126] Jongo, in press, American Journal of Tropical Medicine and Hygiene
6. DMID 11–0042 (NCT02773979) Jan 2017 (completed)	Phase 1 dose escalation with CHMI in Seattle, U.S.A. (one group randomized double-blind, placebo-controlled	CQ	5.12×10^4 x 3 (Days 1, 8, 15); 1.024×10^5 x 3 (Days 1, 8, 15); 1.024×10^5 x 3 (Days 1, 6, 11)	Malaria-naive adults: 21	[127]
7. DMID 15–0052 (NCT02996695) Apr 2017 (completed)	Phase 1, randomized, double-blind placebo-controlled* field efficacy in Mali	CQ	2.048 × 10^5 x 3 (Weeks 1, 5, 9)	Malaria-exposed adults: 31	[167]
8. 17-I-0067 (NCT03083847) Jun 2017 (completed)	Phase 1 dose escalation, regimen condensation with CHMI in Bethesda, U.S.A.	CQ pyrimethamine	5.0×10^4 x 1; 1.0 × 10^5 x 1; 2.0 × 10^5 x 1; 2.0 × 10^5 x 3 (Weeks 1, 5, 9)		[68]
9. TÜCHMI-03 (EudraCT Number: 2018–004523–36) May 2019 (completed)	Phase 1 regimen condensation with CHMI in Germany	CQ	1.1 × 10^5 x 3 (Days 1, 6, 29)	Malaria-naive adults: 14	[128]
10. 19-I-N099 (NCT03952650) Jun 2019 (completed)	Phase 1/2, randomized, double-blind placebo-controlled* field efficacy in Mali	pyrimethamine or CQ	4.0 × 10^5 (Days 1, 29, 57)	Malaria-exposed adults: 4 (with CQ as partner drug) + 158 (with PYR as partner drug)	Sagara and Cook, unpublished
11. IDSPZV1 (NCT03503058) June 2022 (ongoing)	Phase 2, randomized, double-blind placebo-controlled* field efficacy in Indonesia	CQ	2.0 × 10^5 (Days 1, 29, 57)	Malaria-naive adults: 124	Nelwan, unpublished

*The placebo control used in all trials is normal saline.

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