What is the purpose of this trial?
Malaria is a major global health problem. Each year there are more than 200 million cases and over 400,000 deaths each year worldwide. There is a great need for a safe, effective malaria vaccine as the range of malaria medicines is limited and drug resistance is increasing.
Plasmodium vivax (P. vivax) is the second commonest type of malaria parasite. Unlike the most common form, Plasmodium falciparum (P. falciparum), P. vivax is very hard to grow and manipulate in the laboratory so we have a limited understanding of how it infects human red blood cells, how it grows and how the body’s immune system responds to it.
In this study, we are looking for volunteers who will be experimentally infected with malaria on up to three separate occasions, each time by receiving an injection of a tiny amount of red blood containing the P. vivax parasites. This is called a “blood-stage challenge” and will help us develop our understanding of P. vivax malaria, as well as allow us to establish a method that will be used to test out potential future vaccines. 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 they are protected from malaria infection, or if they develop infection more slowly than volunteers who have not been vaccinated.
There is considerable experience performing this type of study with the commonest form of malaria, P. falciparum, but within Europe this sort of deliberate infection has not previously been carried out with P. vivax malaria, although the method has been safely conducted in Australia. This study will therefore be important to demonstrate this type of P. vivax challenge is safe, so we can carry out other studies to test vaccines and understand more about the body’s responses to infection in the future. The first phase of the study took place in January 2019; six healthy volunteers were successfully and safely infected with P. vivax malaria by “blood-stage challenge”. Following treatment to clear the malaria parasite they all made a rapid and full recovery. From this first, small ‘pilot-phase’ of the study we have established the optimal dose required to induce infection and this dose will be used in all subsequent phases of the study.
In areas where malaria is common, people are often infected with malaria on multiple occasions and they can develop an immune response to malaria over time. In order to study the body’s responses to multiple infections, we will infect volunteers up to three times. This will allow us to see if there is any difference between the second and third infection, compared to the first.
What does the trial involve?
Most volunteers in this study will take part in three malaria challenges over the course of 2 years. Two groups will only take part in one challenge. Each malaria challenge has a follow-up period of 3 months. For those taking part in three challenges, each subsequent challenge will take place between 5 and 9 months after the last. After each malaria challenge, we will follow volunteers closely in clinic until they develop malaria infection, taking blood at each visit. As soon as a volunteer develops malaria infection, treatment will be started. There will be further, less frequent, follow-up appointments until approximately 3 months after each challenge. Further information on the study groups can be found in the study information sheet.
Is there any reimbursement for the trial?
Yes, you will be reimbursed at set rates (up to approximately £6855 for participation in three malaria challenges) for your time, inconvenience and travel. Full details of reimbursement can be found in the trial information sheets information sheets.
What are the advantages of taking part?
This study will not benefit you, but the information gained from the trial might help to prevent malaria infection and disease in those who live in areas where malaria is common and in travellers. It is hoped that the method tested in this study will allow future studies to assess possible future vaccines against P. vivax, and ultimately contribute to the development of a safe and effective P. vivax malaria vaccine.
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.