Malaria, VivaxEarly Phase 1NCT03797989
VAC069: A Study of Blood-stage Controlled Human P. Vivax Infection
A Early Phase 1 study testing P. vivax infected inoculum (parasitised red blood cells) in people with Malaria, Vivax, run by University of Oxford at 1 site in United Kingdom.
Trial summary
This is a clinical study to assess the safety and feasibility of Plasmodium vivax (P. vivax) controlled blood-stage human malaria infection (CHMI), by inoculation using a newly created source of P. vivax malaria-infected blood. Read more about this study
- Who is it for?
- Ages 18 to 50 yearsHealthy volunteers can take part
- Conditions the study is for
- Malaria, Vivax
- What is being tested?
- P. vivax infected inoculum (parasitised red blood cells)
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 19 participants
- Where
- 1 siteUnited Kingdom
- Study dates
- 10 Jan 2019to 20 Dec 2022
- Phase
- Early Phase 1
- Are there results?
- Yes, posted in the registrySummary in the doctors' view
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 to 50 years
- All sexes
- Healthy volunteers accepted
- Adult
Who may be able to join
- Healthy adult aged 18 to 50 years.
- Red blood cells positive for the Duffy antigen/chemokine receptor (DARC).
- Normal serum levels of Glucose-6-phosphate dehydrogenase (G6PDH).
- Negative haemoglobinopathy screen
- 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.
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- Women only: Must practice continuous effective contraception for the duration of the clinic visits (first 3 months post-CHMI).
- Agreement to permanently refrain from blood donation
- Written informed consent to participate in the trial.
- Reachable (24/7) by mobile phone during the period between CHMI and completion of all antimalarial treatment.
- Willing to take a curative anti-malarial regimen following CHMI.
- Willing to reside in Oxford for the duration of the study, until antimalarials have been completed.
- Answer all questions on the informed consent quiz correctly.
Who cannot join
- History of clinical malaria (any species).
- Travel to a clearly malaria endemic locality during the study period or within the preceding six months.
- Use of systemic antibiotics with known antimalarial activity within 30 days of CHMI (e.g.trimethoprim-sulfamethoxazole, doxycycline, tetracycline, clindamycin, erythromycin, fluoroquinolones and azithromycin).
- Haemoglobin <120 g/L for a female volunteer or <130 g/L for a male volunteer prior to primary CHMI. (However, for enrolment into secondary and tertiary CHMIs slightly lower haemoglobin values (≤0.5 g/L) will be permitted at the discretion of the Investigator, to account for the blood volume donated during the previous CHMI).
- Receipt of immunoglobulins within the three months prior to enrolment.
- Receipt of blood transfusion at any time in the past.
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- Peripheral venous access unlikely to allow twice daily blood testing (as determined by the Investigator).
- Receipt of an investigational product in the 30 days preceding enrolment, or planned receipt during the study period.
- Prior receipt of an investigational vaccine likely to impact on interpretation of the trial data or the P. vivax parasite as assessed by the Investigator.
- Planned receipt of a COVID-19 vaccine between 2 weeks before the day of CHMI until completion of antimalarial treatment
- 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 malaria infection.
- Pregnancy, lactation or intention to become pregnant during the study.
- Use of medications known to cause prolongation of the QT interval and existing contraindication to the use of Malarone.
- Use of medications known to have a potentially clinically significant interaction with Riamet and Malarone.
- Any clinical condition known to prolong the QT interval.
- History of cardiac arrhythmia, including clinically relevant bradycardia.
- Disturbances of electrolyte balance, e.g. hypokalaemia or hypomagnesaemia.
- Family history of congenital QT prolongation or sudden death.
- Contraindications to the use of both of the proposed anti-malarial medications Riamet and Malarone.
- History of cancer (except basal cell carcinoma of the skin and cervical carcinoma in situ).
- History of serious psychiatric condition that may 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 25 standard UK units every week.
- Suspected or known injecting drug abuse in the 5 years preceding enrolment.
- Hepatitis B surface antigen (HBsAg) detected in serum.
- Seropositive for hepatitis C virus (antibodies to HCV) at screening or at C-7 (unless has taken part in a prior hepatitis C vaccine study with confirmed negative HCV antibodies prior to participation in that study, and negative HCV RNA PCR at screening for this study).
- Positive family history in both 1st AND 2nd degree relatives < 50 years old for cardiac disease.
- Volunteers unable to be closely followed for social, geographic or psychological reasons.
- Any clinically significant abnormal finding on biochemistry or haematology blood tests, urinalysis or clinical examination. In the event of abnormal test results, confirmatory repeat tests will be requested.
- Any other significant disease, disorder, or finding which may significantly increase the risk to the volunteer because of participation in the study, affect the ability of the volunteer to participate in the study or impair interpretation of the study data.
- Inability of the study team to contact the volunteer's GP to confirm medical history and safety to participate.
- Additional exclusion criteria for Groups 6-13: Body weight <50Kg, as measured at screening
- Acute disease, defined as moderate or severe illness with or without fever.
- Current COVID-19 infection, defined as ongoing symptoms with positive COVID-19 PCR swab test taken during current illness or positive COVID-19 PCR swab test within preceding 14 days without symptoms.
- Pregnancy.
- Potential volunteers who are due to have a COVID-19 vaccine in the period between 2 weeks before the day of malaria challenge and expected time of completion of malaria treatment will not be enrolled (estimate up to 3 weeks after day of challenge based on experience in this study to date). If a volunteer receives an appointment for COVID-19 vaccination after they have undergone malaria challenge but before reaching malaria diagnosis criteria, they will be advised to delay their COVID-19 vaccination until after reaching malaria diagnostic criteria and completion of antimalarial treatment. If a participant does not wish to delay their COVID-19 vaccination, they will be treated with antimalarial treatment at that time point and withdrawn from the study but will be encouraged to complete follow-up for safety.
Trial locations and contacts
1 site in 1 country.
United Kingdom1 site
Centre for Clinical Vaccinology & Tropical Medicine
Oxford, Oxfordshire, OX3 7LE
About this study
Official title: VAC069: A Clinical Study to Assess the Safety and Feasibility of Controlled Blood-stage Plasmodium Vivax Human Malaria Infection Through Experimental Inoculation of Cryopreserved Infected Erythrocytes in Healthy Malaria-naïve UK Adults
This is a clinical study to assess the safety and feasibility of Plasmodium vivax (P. vivax) controlled blood-stage human malaria infection (CHMI), by inoculation using a newly created source of P. vivax malaria-infected blood.
25 healthy malaria-naïve UK volunteers, aged 18 - 50, will be recruited through the five phases of the study at the CCVTM, Oxford. Volunteers will undergo primary, secondary and tertiary P. vivax blood-stage challenges, which will be induced by injection of P. vivax infected blood. After the first challenge, the optimal dose for blood-stage CHMI will be selected and used for the second and third challenges. Through each challenge period, volunteers will have blood taken at regular intervals to measure the parasite growth, quantify the sexual parasite forms and assess the immune response to P. vivax infection. Transmission of P. vivax from volunteers to the Anopheline mosquito vectors will also be assessed.
In each challenge, following diagnosis, volunteers will be treated with a standard antimalarial course of oral artemether-lumefantrine (Riamet), given over 60 hours. Volunteers who take part in this study will be involved in the trial for approximately 2 years, receiving each of the three challenges at intervals of approximately 5 (and up to 9) months. Volunteers will be followed for 3 months after their last challenge.
Read the detailed description
This study aims primarily to assess the safety and feasibility of controlled blood-stage human P. vivax malaria infection. This will be the first time that this source of P. vivax infected blood will be utilised and the first P. vivax bloodstage CHMI in Europe. If demonstrated to be safe, it is intended that this parasitised blood bank be used in future CHMI studies to evaluate candidate vaccines.
This study will also assess parasite growth, including quantifying the sexual-stage parasites in the blood, as well as the transmission of P. vivax from volunteers to the Anopheline mosquito vectors and the immune responses in primary, secondary and tertiary P. vivax blood-stage challenge, as further secondary aims. Natural immunity to P. vivax is acquired over time, following repeated exposure. Repeated blood-stage challenge would improve understanding of how the human immune response to P. vivax infected is acquired, and how parasite growth changes in a second or third exposure. Repeated challenges can also be used to test if potential vaccine candidates can protect against repeated malaria infection. If proven to be safe and feasible in this study, this will provide a basis for conducting P. vivax blood-stage re-challenge studies for evaluation of new vaccine candidates.
The study is funded through The Wellcome Trust and MultiViVax, a European Commission Horizon 2020 funded project.
- Conditions
- Malaria, Vivax
- Being tested
- P. vivax infected inoculum (parasitised red blood cells)
- Medical subject headings
- Malaria, Vivax
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
P. vivax infected inoculum (parasitised red blood cells)Biological
In the first controlled human malaria infection (CHMI, Phase A), inoculation of parasitised red blood cells will be at three different doses (1 vial, 1:5 dilution, 1:20 dilution). The optimal inoculation dose will then be selected and administered to all participants in each of the second and third CHMI.
| Study group | Role | What they receive |
|---|---|---|
| Phase A: Group 1 | Experimental | Each volunteer will receive one vial of P. vivax infected inoculum (parasitised red blood cells) at the first blood-stage controlled human malaria infection (CHMI). The optimal dose will be determined following the first CHMI and the selected dose will be administered to all volunteers (Groups 1-3) at both the second and third CHMI. Receives: Biological: P. vivax infected inoculum (parasitised red blood cells) |
| Phase A: Group 2 | Experimental | Each volunteer will receive a fifth of a vial (1:5 dilution) of P. vivax infected inoculum (parasitised red blood cells) at the first blood-stage controlled human malaria infection (CHMI). The optimal dose will be determined following the first CHMI and the selected dose will be administered to all volunteers (Groups 1-3) at both the second and third CHMI. Receives: Biological: P. vivax infected inoculum (parasitised red blood cells) |
| Phase A: Group 3 | Experimental | Each volunteer will receive one twentieth of a vial (1:20 dilution) of P. vivax infected inoculum (parasitised red blood cells) at the first blood-stage controlled human malaria infection (CHMI). The optimal dose will be determined following the first CHMI and the selected dose will be administered to all volunteers (Groups 1-3) at both the second and third CHMI. Receives: Biological: P. vivax infected inoculum (parasitised red blood cells) |
| Phase B: Group 4 | Experimental | The six volunteers from Groups 1, 2 and 3 in will undergo secondary challenge using the optimal inoculum, as determined in Phase A of the study. They will constitute 'Group 4' in Phase B. This will occur approximately eight months (and up to nine months) later after their primary challenge. Receives: Biological: P. vivax infected inoculum (parasitised red blood cells) |
| Phase B: Group 6 | Experimental | Three new malaria naïve volunteers will be recruited to undergo primary challenge using the optimal inoculum, as determined in Phase A of the study. They will act as controls to Group 4. Receives: Biological: P. vivax infected inoculum (parasitised red blood cells) |
| Phase C: Group 5 | Experimental | The six volunteers from Group 4 in Phase B will undergo tertiary challenge, again using the optimal inoculum as determined in Phase A, and will constitute Group 5 in Phase C. This will occur approximately sixteen months (and up to twenty months) later after their secondary challenge. Receives: Biological: P. vivax infected inoculum (parasitised red blood cells) |
| Phase C: Group 7 | Experimental | The three volunteers from Group 6 who underwent primary challenge in Phase B undergo secondary challenge, again using the optimal inoculum as determined in Phase A, and will now form Group 7 in Phase C. This will occur approximately six months (and up to nine months) later after their primary challenge. Receives: Biological: P. vivax infected inoculum (parasitised red blood cells) |
| Phase C: Group 9 | Experimental | Four to eight new malaria-naïve volunteers will be recruited to undergo primary challenge using the optimal inoculum, as determined in Phase A of the study. They will act as controls for Groups 5 and 7. Receives: Biological: P. vivax infected inoculum (parasitised red blood cells) |
| Phase D: Group 8 | Experimental | The three volunteers from Group 7 in Phase C will undergo tertiary challenge, again using the optimal inoculum as determined in Phase A, and will constitute Group 8 in Phase D. This will occur approximately five months (and up to ten months) after their secondary challenge. Receives: Biological: P. vivax infected inoculum (parasitised red blood cells) |
| Phase D: Group 10 | Experimental | The four to eight volunteers from Group 9 in Phase C will undergo secondary challenge, using the optimal inoculum as determined in Phase A, and form Group 10 in Phase D. This will occur approximately six months (and up to nine months) later after their primary challenge. Receives: Biological: P. vivax infected inoculum (parasitised red blood cells) |
| Phase D: Group 12 | Experimental | Four to eight new malaria-naïve volunteers will be recruited to undergo primary challenge using the optimal inoculum, as determined in Phase A of the study. They will act as controls for Groups 8 and 10. Receives: Biological: P. vivax infected inoculum (parasitised red blood cells) |
| Phase E: Group 13 | Experimental | Volunteers from Groups 10 and 12 who completed at least one P. vivax CHMI in Phase D will be re-enrolled into Group 13 to undergo repeat heterlogous CHMI with P. falciparum in Phase E. This will occur occur approximately 12 months after their last P. vivax challenge. Receives: Biological: P. vivax infected inoculum (parasitised red blood cells) |
What is being measured
The primary outcome is the main question the study is designed to answer.
Number of Participants With Serious Adverse Events
Measured: 36 months
Number of Participants Who Developed Infection/Reached Diagnosis Criteria, Used to Select the Optimal Inoculation Dose to Take Forward to Future P. Vivax CHMI Studies Based on a Protocol-specified Algorithm
Choosing the optimal inoculation dose to take forward to future P. vivax CHMI studies will be decided based on the following algorithm:
Ideal choice = the first group (2/2 volunteers) to reach diagnosis criteria (within 21 days). N.B. If both volunteers in Group 1 develop infection AND both volunteers in Group 2 (or 3) reliably develop infection within 5 days of Group 1 (and within the 21-day window) then the lowest dose group should be chosen.
Measured: 3 months
Feasibility of Primary P. Vivax Blood-stage CHMI as Measured by Successful Infection (Development of Detectable Persistent Parasitaemia by Thick Film and qPCR +/- Clinical Symptoms)
Number of participants developing detectablable parasitaemia during primary CHMI with P. vivax (PvW1 clone)
Measured: 36 months
Secondary outcomes (5)
Safety of Secondary and Tertiary P. Vivax Controlled Blood-stage CHMI as Measured by (S)AE Occurrences
Measured: 36 months
Immune Response to Primary, Secondary and Tertiary P. Vivax Pre-treatment
As measured by antibody, B cell and T cell responses through experimental injection of P. vivax infected erythrocytes
Measured: 36 months
Gametocytaemia
As measured by qPCR in primary, secondary and tertiary P. vivax blood-stage CHMI.
Measured: 36 months
Feasibility of Secondary and Tertiary P. Vivax Controlled Blood-stage CHMI as Measured by Successful Infection (Development of Detectable Persistent Parasitaemia by Thick Film and qPCR +/- Clinical Symptoms)
Measured: 36 months
Transmissibility of Gametocytes From the Infected Volunteer to Anopheline Mosquito Vector, Which Will be Assesed by Direct Membrane Feeding Assays (DMFA)
Measured: 36 months
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted9 Jan 2019
- Study start10 Jan 2019
- Primary completion20 Dec 2022
- Study completion20 Dec 2022
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Posted resultsParticipant flow, outcome measures and adverse events reported by the sponsor.
- Publications (4)Papers the sponsor has linked to this study.
- Other trials for Malaria, VivaxStudies of the same condition, open and under way.
- More trials run by University of OxfordThe sponsor's other registered studies.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Early Phase 1
- Primary purpose
- Other
- Allocation
- Non-randomised
- Intervention model
- Parallel groups
- Masking
- None (open label)
- Enrolment
- 19 participants (actual)
Sponsor and investigators
- Lead sponsor
- University of Oxford
- Sponsor type
- University, hospital or other
- Responsible party
- Sponsor
- Investigators
- Angela M Minassian, MBBS MA DPhil MRCP FRCPath, Principal investigator, University of Oxford
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT03797989
- Sponsor's protocol ID
- VAC069
- Status last verified
- Mar 2023
- First submitted
- 29 Nov 2018
- Last updated
- 25 Apr 2025
- Results posted
- Yes, on ClinicalTrials.gov
- Data monitoring committee
- Yes
- FDA-regulated drug
- No
- FDA-regulated device
- No
Publications
Hou MM, Harding AC, Barber NM, Kundu P, Bach FA, Salkeld J, Themistocleous Y, Greenwood NM, Cho JS, Barrett JR, Nugent FL, Rawlinson TA, Hodgson SH, Khozoee B, Mac Lochlainn DJ, Cowan RE, Poulton ID, Baker M, Kingham L, Mitton CH, Platt A, Lopez Ramon R, Ramos Lopez F, Thomas M, Skinner K, Quinkert D, Pipini D, Lias AM, Bardelli M, Edwards NJ, Donnellan FR, Biswas S, Rayner JC, Nielsen CM, Silk SE, Draper SJ, Nahrendorf W, Spence PJ, Minassian AM. Development of clinical immunity to Plasmodium vivax following repeat controlled human malaria infection. Nat Commun. 2025 Sep 25;16(1):8385. doi: 10.1038/s41467-025-63104-y.
PubMed 40998768Bach FA, Munoz Sandoval D, Mazurczyk M, Themistocleous Y, Rawlinson TA, Harding AC, Kemp A, Silk SE, Barrett JR, Edwards NJ, Ivens A, Rayner JC, Minassian AM, Napolitani G, Draper SJ, Spence PJ. A systematic analysis of the human immune response to Plasmodium vivax. J Clin Invest. 2023 Oct 16;133(20):e152463. doi: 10.1172/JCI152463.
PubMed 37616070Hou MM, Barrett JR, Themistocleous Y, Rawlinson TA, Diouf A, Martinez FJ, Nielsen CM, Lias AM, King LDW, Edwards NJ, Greenwood NM, Kingham L, Poulton ID, Khozoee B, Goh C, Mac Lochlainn DJ, Salkeld J, Guilotte-Blisnick M, Huon C, Mohring F, Reimer JM, Chauhan VS, Mukherjee P, Biswas S, Taylor IJ, Lawrie AM, Cho JS, Nugent FL, Long CA, Moon RW, Miura K, Silk SE, Chitnis CE, Minassian AM, Draper SJ. Impact of a blood-stage vaccine on Plasmodium vivax malaria. medRxiv [Preprint]. 2022 May 30:2022.05.27.22275375. doi: 10.1101/2022.05.27.22275375.
PubMed 35664997Minassian AM, Themistocleous Y, Silk SE, Barrett JR, Kemp A, Quinkert D, Nielsen CM, Edwards NJ, Rawlinson TA, Ramos Lopez F, Roobsoong W, Ellis KJ, Cho JS, Aunin E, Otto TD, Reid AJ, Bach FA, Labbe GM, Poulton ID, Marini A, Zaric M, Mulatier M, Lopez Ramon R, Baker M, Mitton CH, Sousa JC, Rachaphaew N, Kumpitak C, Maneechai N, Suansomjit C, Piteekan T, Hou MM, Khozoee B, McHugh K, Roberts DJ, Lawrie AM, Blagborough AM, Nugent FL, Taylor IJ, Johnson KJ, Spence PJ, Sattabongkot J, Biswas S, Rayner JC, Draper SJ. Controlled human malaria infection with a clone of Plasmodium vivax with high-quality genome assembly. JCI Insight. 2021 Dec 8;6(23):e152465. doi: 10.1172/jci.insight.152465.
PubMed 34609964
Study at a glance
From the registry record, last updated by the sponsor on 25 Apr 2025. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- VAC069: A Clinical Study to Assess the Safety and Feasibility of Controlled Blood-stage Plasmodium Vivax Human Malaria Infection Through Experimental Inoculation of Cryopreserved Infected Erythrocytes in Healthy Malaria-naïve UK Adults
- ClinicalTrials.gov ID
- NCT03797989
- Acronym / sponsor ID
- VAC069
- Conditions
- Malaria, Vivax
- Phase
- Early Phase 1
- Study type
- Interventional
- Recruitment status
- Completed
- Enrolment
- 19 participants (actual)
- Lead sponsor
- University of OxfordUniversity, hospital or other
- Study start
- 10 Jan 2019 (actual)
- Primary completion
- 20 Dec 2022 (actual)
- Study completion
- 20 Dec 2022 (actual)
- First posted
- 9 Jan 2019 (actual)
- Results
- Posted 25 Apr 2025
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
This is a clinical study to assess the safety and feasibility of Plasmodium vivax (P. vivax) controlled blood-stage human malaria infection (CHMI), by inoculation using a newly created source of P. vivax malaria-infected blood.
25 healthy malaria-naïve UK volunteers, aged 18 - 50, will be recruited through the five phases of the study at the CCVTM, Oxford. Volunteers will undergo primary, secondary and tertiary P. vivax blood-stage challenges, which will be induced by injection of P. vivax infected blood. After the first challenge, the optimal dose for blood-stage CHMI will be selected and used for the second and third challenges. Through each challenge period, volunteers will have blood taken at regular intervals to measure the parasite growth, quantify the sexual parasite forms and assess the immune response to P. vivax infection. Transmission of P. vivax from volunteers to the Anopheline mosquito vectors will also be assessed.
In each challenge, following diagnosis, volunteers will be treated with a standard antimalarial course of oral artemether-lumefantrine (Riamet), given over 60 hours. Volunteers who take part in this study will be involved in the trial for approximately 2 years, receiving each of the three challenges at intervals of approximately 5 (and up to 9) months. Volunteers will be followed for 3 months after their last challenge.
Detailed description
This study aims primarily to assess the safety and feasibility of controlled blood-stage human P. vivax malaria infection. This will be the first time that this source of P. vivax infected blood will be utilised and the first P. vivax bloodstage CHMI in Europe. If demonstrated to be safe, it is intended that this parasitised blood bank be used in future CHMI studies to evaluate candidate vaccines.
This study will also assess parasite growth, including quantifying the sexual-stage parasites in the blood, as well as the transmission of P. vivax from volunteers to the Anopheline mosquito vectors and the immune responses in primary, secondary and tertiary P. vivax blood-stage challenge, as further secondary aims. Natural immunity to P. vivax is acquired over time, following repeated exposure. Repeated blood-stage challenge would improve understanding of how the human immune response to P. vivax infected is acquired, and how parasite growth changes in a second or third exposure. Repeated challenges can also be used to test if potential vaccine candidates can protect against repeated malaria infection. If proven to be safe and feasible in this study, this will provide a basis for conducting P. vivax blood-stage re-challenge studies for evaluation of new vaccine candidates.
The study is funded through The Wellcome Trust and MultiViVax, a European Commission Horizon 2020 funded project.
Study design
- Primary purpose
- Other
- Allocation
- Non-randomised
- Intervention model
- Parallel groups
- Masking
- None (open label)
- Number of arms
- 12
| Arm | Type | Receives |
|---|---|---|
| Phase A: Group 1 | Experimental | Biological: P. vivax infected inoculum (parasitised red blood cells)Each volunteer will receive one vial of P. vivax infected inoculum (parasitised red blood cells) at the first blood-stage controlled human malaria infection (CHMI). The optimal dose will be determined following the first CHMI and the selected dose will be administered to all volunteers (Groups 1-3) at both the second and third CHMI. |
| Phase A: Group 2 | Experimental | Biological: P. vivax infected inoculum (parasitised red blood cells)Each volunteer will receive a fifth of a vial (1:5 dilution) of P. vivax infected inoculum (parasitised red blood cells) at the first blood-stage controlled human malaria infection (CHMI). The optimal dose will be determined following the first CHMI and the selected dose will be administered to all volunteers (Groups 1-3) at both the second and third CHMI. |
| Phase A: Group 3 | Experimental | Biological: P. vivax infected inoculum (parasitised red blood cells)Each volunteer will receive one twentieth of a vial (1:20 dilution) of P. vivax infected inoculum (parasitised red blood cells) at the first blood-stage controlled human malaria infection (CHMI). The optimal dose will be determined following the first CHMI and the selected dose will be administered to all volunteers (Groups 1-3) at both the second and third CHMI. |
| Phase B: Group 4 | Experimental | Biological: P. vivax infected inoculum (parasitised red blood cells)The six volunteers from Groups 1, 2 and 3 in will undergo secondary challenge using the optimal inoculum, as determined in Phase A of the study. They will constitute 'Group 4' in Phase B. This will occur approximately eight months (and up to nine months) later after their primary challenge. |
| Phase B: Group 6 | Experimental | Biological: P. vivax infected inoculum (parasitised red blood cells)Three new malaria naïve volunteers will be recruited to undergo primary challenge using the optimal inoculum, as determined in Phase A of the study. They will act as controls to Group 4. |
| Phase C: Group 5 | Experimental | Biological: P. vivax infected inoculum (parasitised red blood cells)The six volunteers from Group 4 in Phase B will undergo tertiary challenge, again using the optimal inoculum as determined in Phase A, and will constitute Group 5 in Phase C. This will occur approximately sixteen months (and up to twenty months) later after their secondary challenge. |
| Phase C: Group 7 | Experimental | Biological: P. vivax infected inoculum (parasitised red blood cells)The three volunteers from Group 6 who underwent primary challenge in Phase B undergo secondary challenge, again using the optimal inoculum as determined in Phase A, and will now form Group 7 in Phase C. This will occur approximately six months (and up to nine months) later after their primary challenge. |
| Phase C: Group 9 | Experimental | Biological: P. vivax infected inoculum (parasitised red blood cells)Four to eight new malaria-naïve volunteers will be recruited to undergo primary challenge using the optimal inoculum, as determined in Phase A of the study. They will act as controls for Groups 5 and 7. |
| Phase D: Group 8 | Experimental | Biological: P. vivax infected inoculum (parasitised red blood cells)The three volunteers from Group 7 in Phase C will undergo tertiary challenge, again using the optimal inoculum as determined in Phase A, and will constitute Group 8 in Phase D. This will occur approximately five months (and up to ten months) after their secondary challenge. |
| Phase D: Group 10 | Experimental | Biological: P. vivax infected inoculum (parasitised red blood cells)The four to eight volunteers from Group 9 in Phase C will undergo secondary challenge, using the optimal inoculum as determined in Phase A, and form Group 10 in Phase D. This will occur approximately six months (and up to nine months) later after their primary challenge. |
| Phase D: Group 12 | Experimental | Biological: P. vivax infected inoculum (parasitised red blood cells)Four to eight new malaria-naïve volunteers will be recruited to undergo primary challenge using the optimal inoculum, as determined in Phase A of the study. They will act as controls for Groups 8 and 10. |
| Phase E: Group 13 | Experimental | Biological: P. vivax infected inoculum (parasitised red blood cells)Volunteers from Groups 10 and 12 who completed at least one P. vivax CHMI in Phase D will be re-enrolled into Group 13 to undergo repeat heterlogous CHMI with P. falciparum in Phase E. This will occur occur approximately 12 months after their last P. vivax challenge. |
Who may qualify
- Ages
- 18 to 50 years
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Adult
Key inclusion criteria (13 listed)
- Healthy adult aged 18 to 50 years.
- Red blood cells positive for the Duffy antigen/chemokine receptor (DARC).
- Normal serum levels of Glucose-6-phosphate dehydrogenase (G6PDH).
- Negative haemoglobinopathy screen
- Able and willing (in the Investigator's opinion) to comply with all study requirements.
Key exclusion criteria (37 listed)
- History of clinical malaria (any species).
- Travel to a clearly malaria endemic locality during the study period or within the preceding six months.
- Use of systemic antibiotics with known antimalarial activity within 30 days of CHMI (e.g.trimethoprim-sulfamethoxazole, doxycycline, tetracycline, clindamycin, erythromycin, fluoroquinolones and azithromycin).
- Haemoglobin <120 g/L for a female volunteer or <130 g/L for a male volunteer prior to primary CHMI. (However, for enrolment into secondary and tertiary CHMIs slightly lower haemoglobin values (≤0.5 g/L) will be permitted at the discretion of the Investigator, to account for the blood volume donated during the previous CHMI).
- Receipt of immunoglobulins within the three months prior to enrolment.
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| P. vivax infected inoculum (parasitised red blood cells)In the first controlled human malaria infection (CHMI, Phase A), inoculation of parasitised red blood cells will be at three different doses (1 vial, 1:5 dilution, 1:20 dilution). The optimal inoculation dose will then be selected and administered to all participants in each of the second and third CHMI. | Biological | Phase A: Group 1, Phase A: Group 2, Phase A: Group 3, Phase B: Group 4, Phase B: Group 6, Phase C: Group 5, Phase C: Group 7, Phase C: Group 9, Phase D: Group 10, Phase D: Group 12, Phase D: Group 8, Phase E: Group 13 |
Primary outcome
Number of Participants With Serious Adverse Events
Time frame: 36 months
Number of Participants Who Developed Infection/Reached Diagnosis Criteria, Used to Select the Optimal Inoculation Dose to Take Forward to Future P. Vivax CHMI Studies Based on a Protocol-specified Algorithm
Time frame: 3 months
Choosing the optimal inoculation dose to take forward to future P. vivax CHMI studies will be decided based on the following algorithm: Ideal choice = the first group (2/2 volunteers) to reach diagnosis criteria (within 21 days). N.B. If both volunteers in Group 1 develop infection AND both volunteers in Group 2 (or 3) reliably develop infection within 5 days of Group 1 (and within the 21-day window) then the lowest dose group should be chosen.
Feasibility of Primary P. Vivax Blood-stage CHMI as Measured by Successful Infection (Development of Detectable Persistent Parasitaemia by Thick Film and qPCR +/- Clinical Symptoms)
Time frame: 36 months
Number of participants developing detectablable parasitaemia during primary CHMI with P. vivax (PvW1 clone)
5 secondary outcomes
Safety of Secondary and Tertiary P. Vivax Controlled Blood-stage CHMI as Measured by (S)AE Occurrences
Time frame: 36 months
Immune Response to Primary, Secondary and Tertiary P. Vivax Pre-treatment
Time frame: 36 months
Gametocytaemia
Time frame: 36 months
Feasibility of Secondary and Tertiary P. Vivax Controlled Blood-stage CHMI as Measured by Successful Infection (Development of Detectable Persistent Parasitaemia by Thick Film and qPCR +/- Clinical Symptoms)
Time frame: 36 months
Transmissibility of Gametocytes From the Infected Volunteer to Anopheline Mosquito Vector, Which Will be Assesed by Direct Membrane Feeding Assays (DMFA)
Time frame: 36 months
Results and safety
Loading the posted results from ClinicalTrials.gov…
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 25 Apr 2025.
- Posted resultsParticipant flow, baseline, all outcome measures and adverse events.
- Derived from this study: PubMed 40998768Hou MM, Harding AC, Barber NM, Kundu P, Bach FA, Salkeld J, Themistocleous Y, Greenwood NM, Cho JS, Barrett JR, Nugent FL, Rawlinson TA, Hodgson SH, Khozoee B, Mac Lochlainn DJ, Cowan RE, Poulton ID, Baker M, Kingham L, Mitton CH, Platt A, Lopez Ramon R, Ramos Lopez F, Thomas M, Skinner K, Quinkert D, Pipini D, Lias AM, Bardelli M, Edwards NJ, Donnellan FR, Biswas S, Rayner JC, Nielsen CM, Silk SE, Draper SJ, Nahrendorf W, Spence PJ, Minassian AM. Development of clinical immunity to Plasmodium vivax following repeat controlled human malaria infection. Nat Commun. 2025 Sep 25;16(1):8385. doi: 10.1038/s41467-025-63104-y.
- Derived from this study: PubMed 37616070Bach FA, Munoz Sandoval D, Mazurczyk M, Themistocleous Y, Rawlinson TA, Harding AC, Kemp A, Silk SE, Barrett JR, Edwards NJ, Ivens A, Rayner JC, Minassian AM, Napolitani G, Draper SJ, Spence PJ. A systematic analysis of the human immune response to Plasmodium vivax. J Clin Invest. 2023 Oct 16;133(20):e152463. doi: 10.1172/JCI152463.
- Derived from this study: PubMed 35664997Hou MM, Barrett JR, Themistocleous Y, Rawlinson TA, Diouf A, Martinez FJ, Nielsen CM, Lias AM, King LDW, Edwards NJ, Greenwood NM, Kingham L, Poulton ID, Khozoee B, Goh C, Mac Lochlainn DJ, Salkeld J, Guilotte-Blisnick M, Huon C, Mohring F, Reimer JM, Chauhan VS, Mukherjee P, Biswas S, Taylor IJ, Lawrie AM, Cho JS, Nugent FL, Long CA, Moon RW, Miura K, Silk SE, Chitnis CE, Minassian AM, Draper SJ. Impact of a blood-stage vaccine on Plasmodium vivax malaria. medRxiv [Preprint]. 2022 May 30:2022.05.27.22275375. doi: 10.1101/2022.05.27.22275375.
- Derived from this study: PubMed 34609964Minassian AM, Themistocleous Y, Silk SE, Barrett JR, Kemp A, Quinkert D, Nielsen CM, Edwards NJ, Rawlinson TA, Ramos Lopez F, Roobsoong W, Ellis KJ, Cho JS, Aunin E, Otto TD, Reid AJ, Bach FA, Labbe GM, Poulton ID, Marini A, Zaric M, Mulatier M, Lopez Ramon R, Baker M, Mitton CH, Sousa JC, Rachaphaew N, Kumpitak C, Maneechai N, Suansomjit C, Piteekan T, Hou MM, Khozoee B, McHugh K, Roberts DJ, Lawrie AM, Blagborough AM, Nugent FL, Taylor IJ, Johnson KJ, Spence PJ, Sattabongkot J, Biswas S, Rayner JC, Draper SJ. Controlled human malaria infection with a clone of Plasmodium vivax with high-quality genome assembly. JCI Insight. 2021 Dec 8;6(23):e152465. doi: 10.1172/jci.insight.152465.
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part. This study is not recruiting at the moment.
Angela M Minassian, MBBS MA DPhil MRCP FRCPath principal investigator
University of Oxford
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A Early Phase 1 study testing P. vivax infected inoculum (parasitised red blood cells) in people with Malaria, Vivax, run by University of Oxford at 1 site in United Kingdom.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 13 inclusion and 37 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: finished, as of the sponsor's last update on 25 Apr 2025. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in United Kingdom. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
What does this phase mean?
Early Phase 1 (sometimes called Phase 0) studies give a very small amount of a treatment to a few people, mainly to see how the body handles it.
Not every study follows the same path, and some studies (observational studies, device studies) have no phase.
Are results available for this study?
Yes. Results are posted in the registry (first posted 25 Apr 2025). A summary is in the For doctors view, and the full results are on ClinicalTrials.gov.
How can a doctor refer a patient or contact the research team?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Number of Participants With Serious Adverse Events (time frame: 36 months). The study lists 3 primary outcomes in all. It is what the study was designed to measure, not a finding.
Where can I read the original study information?
On the ClinicalTrials.gov record for NCT03797989, which also lists 4 linked publications.
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 25 Apr 2025.