A Phase I/IIa Sporozoite challenge study to assess the safety and protective efficacy of adjuvanted R21 at two different doses and the combination malaria vaccine candidate regimen of adjuvanted R21 + ChAd63 and MVA Encoding ME-TRAP.

Vaccination phases and challenge procedures have been staggered over the trial period into 2 parts, challenges A and B.

Challenge A:

• Groups 1-3 consist of volunteers receiving either R21 alone or R21 + ChAd63-MVA ME-TRAP followed by CHMI by sporozoite challenge (mosquito bite) at week 12. Twelve volunteers will be recruited to each group.
• Group 4a will serve as infectivity controls, these volunteers will not be vaccinated.

Challenge B:

• Sterilely protected volunteers in groups 1 – 3 may be rechallenged to assess durability of efficacy, 5-12 months after the initial challenge.
• Groups 5-7 will also be enrolled to participate in challenge B.
• Group 5 (8 volunteers) will test the efficacy of standard dose R21 with a fractional third dose followed by CHMI at week 12.
• Group 6 will test the long-term efficacy of the standard dose R21 vaccination regimen (volunteers in this group will have already received their vaccinations whilst enrolled in the VAC053 malaria trial and will therefore not receive any additional vaccinations before undergoing challenge).
• Group 7 (8 volunteers) will test the efficacy of a two dose R21 vaccination regimen followed by CHMI at week 8.
• Group 4b will serve as infectivity controls for groups 5-7 and sterilely protected group 1-3 volunteers. Group 4c volunteers will be used as infectivity controls if any volunteers from groups 5 and 7 are rechallenged.

NCT number: NCT02905019

Study type: Interventional

Enrollment: 63 participants

Allocation: Randomized

Intervention model: Parallel Assignment

Masking: Single

Primary purpose: Prevention

Clinical trial registration

Product Development
Vaccines (Immune Correlates)

Aug 2016 — Dec 2017

United Kingdom

Multi-Stage Malaria Vaccine Consortium (MMVC): A four-strike vaccine against malaria