Two-arm, randomized, double-blinded and controlled clinical trial to first assess the safety and tolerability of the vaccine in a Phase 1b trial and proceed to assess its efficacy against clinical malaria in young children living in highly seasonal malaria areas of Mali
This study is designed to be executed in two steps to achieve the primary efficacy objective: The first step is a Phase 1b safety study, involving injections in a small safety subgroup for each dose before age-de-escalation into the younger age group and then proceeding to the second step of dosing the corresponding injection in the larger Phase 2b efficacy cohort. Vaccination of the Phase 2b cohort will require an acceptable reactogenicity data over the first week following the corresponding vaccination of the older and younger age groups in the Phase 1 subgroup. The study DSMB will be charged with this review and ensuring that vaccination proceeds only if the reactogenicity profile meet study "go" criteria (Table 1). The objectives of each phase are: Phase 1b: The primary objective is to assess the safety and tolerability of the vaccine for each injection. The secondary objective is to evaluate the immune response to the vaccine and safety for up to 12 months after the first dose. Phase 2b: The primary objective is to assess the efficacy in young children\* against clinical malaria\*\* during one transmission season. The timeline for the primary analysis assessment is from 14 days to 6 months after Dose 3. Should the primary analysis data demonstrate that the vaccine gives good efficacy, a boost vaccination will be programmed to be administered to willing subjects before the start of the subsequent transmission season. The study protocol will be amended with the precise details in this event.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
PREVENTION
Masking
QUADRUPLE
Enrollment
465
30 microgram MSP3-CRM-Vac4All protein extemporaneously formulated with Alhydrogel® adjuvant
Control vaccine
Malaria Research and Training Center (MRTC), University of Sciences Techniques and Technologies of Bamako, Mali
Bamako, Mali
RECRUITINGProtective Efficacy against Clinical Malaria
To assess the efficacy of 30 µg MSP3-CRM-Vac4All/Alhydrogel® vaccine in children ages 12-60 months old, against clinical malaria occurring over one transmission season. The primary efficacy outcome is clinical malaria, with the primary case definition of clinical malaria episodes defined as a febrile episode with an axillary temperature of ≥ 37.5ºC with P. falciparum parasitemia ≥5000/µL
Time frame: The timeline for assessment will be from 14 days to 6 months after Dose 3.
Efficacy- different definitions of malaria fever and parasite thresholds on microscopy
To compare efficacy against clinical malaria for different case definitions using * Fever thresholds that are higher than 37.5ºC, such as 38.5ºC and 39.5ºC * History of fever instead of measured fever * Different parasitemia by microscopy thresholds \[any parasitemia, 1000, 10,000 and 20,000/µL\] Efficacy outcomes * clinical malaria episodes defined as a febrile episode with an axillary temperature of ≥ 38.5ºC with P. falciparum parasitemia ≥5000/µL or ≥ 39.5ºC with P. falciparum parasitemia ≥5000/µL or * clinical malaria episodes defined as history of fever with P. falciparum parasitemia of the following levels: any parasitemia, 1000, 10,000 and 20,000/µL clinical malaria episodes defined as a febrile episode with an axillary temperature of ≥ 38.5ºC with or ≥ 39.5ºC with P. falciparum parasitemia of the following levels: any parasitemia, 1000, 10,000 and 20,000/µL
Time frame: For 12 months after first vaccination
Efficacy duration
To assess the efficacy of MSP3-CRM-Vac4All/Alhydrogel® in young children against clinical malaria occurring during the 12 months following dose 3.
Time frame: For 12 months following the first vaccination
Efficacy against first malaria episodes
To assess the efficacy of MSP3-CRM-Vac4All/Alhydrogel® in young children against first clinical malaria episodes occurring from over the 6 month period 14 days after 2nd and 3rd vaccination and up to the end of study follow-up (12 months after first vaccination). The efficacy outcome is first episode of clinical malaria, with the case definition of clinical malaria episodes defined as a febrile episode with an axillary temperature of ≥ 37.5ºC with P. falciparum parasitemia ≥5000/µL
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Time frame: From 14 days post 2nd or 3rd vaccination to 6 months following and up to the end of study follow-up (12 months after first vaccination
Efficacy (conditional boost)
To assess the efficacy of MSP3-CRM-Vac4All/Alhydrogel® in young children against clinical malaria occurring The efficacy outcome is clinical malaria, with the primary case definition of clinical malaria episodes defined as a febrile episode with an axillary temperature of ≥ 37.5ºC with P. falciparum parasitemia ≥5000/µL
Time frame: For the 6 months following boost vaccination
Efficacy (conditional boost)
To assess the efficacy of MSP3-CRM-Vac4All/Alhydrogel® in young children against clinical malaria occurring. The efficacy outcome is clinical malaria, with the primary case definition of clinical malaria episodes defined as a febrile episode with an axillary temperature of ≥ 37.5ºC with P. falciparum parasitemia ≥5000/µL
Time frame: For the 12 months following boost vaccination
Number of adverse events
To assess the safety and reactogenicity of 3 doses of 30 µg MSP3-CRM-Vac4All/Alhydrogel® given at D0, D28 and D56 in healthy young children
Time frame: During the month following each vaccination, and 6 months and 12 months after first vaccination.
Number of adverse events for conditional boost vaccination
Safety and reactogenicity of boost vaccination doses of MSP3-CRM-Vac4All/Alhydrogel® in healthy young children
Time frame: At one month, 6 month and 12 months following boost vaccination
Immune response
To examine the duration of immune responses of a 3-dose regimen of during periods corresponding to that used for primary and other secondary efficacy endpoints as measured through a \> 5-fold decrease of MSP3-specific serum IgG antibody titers after each vaccination in comparison to baseline levels (14 days post last dose)
Time frame: From 14 days post last dose to up to a month after last dose, 6 months after last dose and 12 months after first dose
Immune response
To determine immunogenicity in terms of the proportion with titres either more than 3SD above the median for negative controls (positive) or at least 50% of the positive controls (strongly positive) after dose 3.
Time frame: A month after dose 3
Parasite densities
To measure effect on parasitemia by comparing parasite densities in malaria episodes occurring in vaccinees compared to control
Time frame: From vaccination to up to 6 months after last dose and 12 months after first dose.