It is “a historic day,” says WHO chief Tedros Adhanom Ghebreyesus. And: the vaccine is “a gift for the world”. Because the WHO has now recommended the widespread use of a vaccine against malaria for the first time.
Malaria is caused by parasites that are transmitted to humans by infected mosquitoes. Hundreds of thousands of people die from it every year, especially children under the age of five.
Peter Kremsner is an infectiologist, tropical medicine specialist and director at the Institute for Tropical Medicine at the University of Tübingen. He was involved in clinical trials for the Mosquirix vaccine. Deutschlandfunk reached him shortly before the broadcast in his research center in Gabon.
The interview in full
Michael Bödekker: Mr. Kremsner, how exactly does this vaccine work?
Peter Kremsner: The vaccine is part of the effective protein, which is the most important surface protein of the sporozoites.
Böddeker: Sporozoites, do you have to explain again briefly, this is a kind of intermediate step of this parasite in its development?
Kremsner: The sporozoites are those malaria parasites that are in the mosquito’s salivary gland and that are transmitted to humans when the infected mosquito bites. And that was cut out, used and provided with adjuvants in such a way that it gives a very good immune response and is also well tolerated and also very effective at the same time.
“A first step, a milestone”
Böddeker: It was a historic day, that’s what the WHO chief called it, is that how you see it?
Kremsner: In any case, it is the first anti-parasitic vaccination that has received prequalification from the World Health Organization for use in medicine – in humans, there are already some in animals. So that’s something very special. We now hope that the actual approvals and application will follow as quickly as possible in the African countries. The phase III study, the actual approval study, took place many years ago, and six years ago the European approval authority issued a positive evaluation of Article 58. In other words, there was something similar in the approval process, but the WHO still wanted these implementation studies, which have now been completed and which have confirmed that this is really very good.
Böddeker: Very good, you say, but the effectiveness of this vaccine is not that high in comparison with other vaccines that are available, especially in infants and young children, who are particularly at risk from malaria, and the protective effect is also decreasing over time. Is all this really enough to ensure that this vaccine is already being used widely?
30 percent effective over five years
Kremsner: Of course, the effectiveness is not quite as good as we would like, but in the first six months there is an effectiveness of about two thirds, around 60, 70 percent is the effectiveness. Then it decreases, it is still around 35 percent after four years. That’s pretty good when you consider that we’ve been researching malaria vaccines for a hundred years. It is the first to get this far and it is a breakthrough in that respect and I hope the vaccine will be used now. But I also hope that we can achieve better efficacy with other vaccines where our turn comes – that is what it looks like at the moment – and then also improve the malaria vaccine. But that is a very important first step, a milestone.
Böddeker: We can perhaps talk a little more about these alternatives, first of all about Mosquirix, the vaccine that the WHO is now recommending: Although it works, you said it is less effective than one would wish, but it does exist not only the effects but also reports of side effects. What is the current state of knowledge about the side effects?
Safe and compatible
Kremsner: Yes, of course there are side effects as with any vaccine or drug in general, and these are reactions at the injection site, but also fever or malaise that occur after the vaccination. That was already so known from the registration study, that has now been confirmed, but nothing has emerged, no pattern of serious side effects, even with this huge study that has now taken place and that shows that the vaccine is safe and also is properly tolerated.
Böddeker: You have just mentioned that there are other vaccines that are being developed. The WHO has just recommended Mosquirix, but these other approaches that you are also working on, how advanced is the research now?
Further vaccines against malaria in the pipeline
Kremsner: That is now well advanced, especially the vaccine approaches, where we take the weakened sporozoites, are very advanced. We are now planning a registration study, which should begin early next year with the most advanced candidate. This is a sporozoite vaccine where the sporozoites are irradiated before being injected. After they have penetrated the liver cells, they can no longer multiply, make a very good immune response and lead to efficacy rates of around 85 percent in the first phase II trials. We now want to show this clearly again in a phase III study and get the vaccine approved.
Böddeker: Now there is this vaccine recommended by the WHO, other approaches are being developed – what would you say, where do we stand now in the overall fight against malaria?
Kremsner: This looks very good. There are also other measures that we have, for example the nets, i.e. bed nets, including bed nets impregnated with insecticides, impregnated bed nets, which are very effective. There is prompt diagnosis and then therapy with what are actually very good therapeutics, which you have to develop again and again because the parasites are resistant. But basically we already have some very good opportunities to put control measures in place, and vaccination is now the next step. And if we have a very effective vaccine that is 80, 90 percent effective, then we really have something to eradicate malaria as well.
Statements by our interlocutors reflect their own views. Deutschlandfunk does not adopt statements made by its interlocutors in interviews and discussions as its own.