This study will be one of the first to test whether a vaccine can prevent or slow P. vivax malaria infection. A safe and effective vaccine would significantly reduce the global health burden caused by P. vivax malaria but unfortunately, no vaccine is yet available. In this study, we are looking for volunteers who will be experimentally infected with P. vivax malaria after receiving two new P. vivax malaria vaccines, called ChAd63 PvDBP and MVA PvDBP vaccines. We have previously tested these vaccines in a small initial clinical study to evaluate their safety. In this previous study, we also looked at the body’s immune response to vaccination and the results look promising.
Now, in this trial, we will assess whether the vaccines will be effective at preventing or slowing malaria infection. Ultimately, in order to test whether a potential new vaccine works, we need to be able to “challenge” vaccinated volunteers with P. vivax malaria infection. We can do this by deliberately infecting volunteers who have been vaccinated, then observing to see if there is a difference in the number of people who develop malaria and the speed at which the infection develops, compared to volunteers who have not been vaccinated. As soon as a volunteer is diagnosed with malaria, they will be started on antimalarial treatment.
What does the trial involve?
Volunteers who take part in this study will be involved for approximately 1 year and attend up to 60 visits.
Each volunteer will receive the ChAd63 PvDBP vaccine first, followed by MVA PvDBP approximately 8 weeks later. Both vaccines are given by injection into the muscle, usually into the upper arm. After each vaccination, we will see volunteers in clinic at regular intervals to assess for
side effects and take blood samples to analyse the body’s immune response to the vaccines.
Around 4 weeks after the second vaccination, we will deliberately infect volunteers with P. vivax malaria by injecting a tiny amount of malaria infected blood into the vein. Deliberately infecting volunteers in this way is called a malaria challenge.
Following challenge, we will observe volunteers closely to see if they develop symptoms of malaria. At the same time, we will take blood daily or twice daily to measure the parasite growth in their blood and analyse the immune response. If volunteers develop malaria (confirmed by detecting parasites in the blood), we will start malaria treatment to clear the infection.
After completing treatment, we will see volunteers for at four further follow-up visits until 1 year after the first vaccination.
Is there any reimbursement for the trial?
Yes, you will be reimbursed at set rates (up to £3320) for your time, inconvenience and travel. Full details of reimbursement can be found in the trial information sheets.
What are the advantages of taking part?
This study will not benefit you, but the information gained from the trial might help in the development of a safe and effective P. vivax malaria vaccine, to prevent infection and disease in those who live in areas where P. vivax malaria is common, as well as travellers. At present, there is no vaccine for P. vivax malaria licensed anywhere in the world.
It is important to be clear that participating in this study will not render you immune to malaria. It is crucial that you follow recommendations for malaria prophylaxis if and when you travel to a malaria-endemic region in the future.
Are there any risks from taking part in the study?
The risks of taking part in this study are very low provided that you return for follow-up as in the information sheet.
What will happen if I don’t want to carry on with the study?
If at any time after agreeing to participate you change your mind about being involved with this study, you are free to withdraw without giving a reason. Your decision will not result in any penalty, or loss of benefits to which you are otherwise entitled. However, if you are enrolled and
wish to leave after malaria challenge then you must take the anti-malarial treatment course because of the potentially very serious consequences of untreated malaria infection. Your compensation would be paid as a proportion of the total compensation according to the length of your participation.
If you think you may be interested in participating in this trial, please complete our online pre-screen questionnaire.
A member of our team will then be in contact with you.