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Q&A with Kemri's Lucas Otieno on malaria vaccine

Saturday April 25 2015
EAinvestigatorsofMalari

Lucas Otieno, a principal investigators at the Kenya Medical Research Institute (Kemri). PHOTO | FILE

The results for the final trials of malaria vaccine RTS,S have been released. Christabel Ligami spoke to one of the principal investigators at the Kenya Medical Research Institute Lucas Otieno on the status of the vaccine research.

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How would you rate the malaria vaccines currently under investigation?

There are no licensed malaria vaccines as per the World Health Organisation’s listing of such projects. Many are in early phases of clinical trials. The most clinically advanced malaria vaccine candidate in the research pipeline is the RTS,S, whose clinical testing is at least 5-10 years ahead of other candidate malaria vaccines.

When will the RTS,S vaccine be available in Africa?

Given that the results of the RTS,S Phase III trial show sufficient evidence of protection and safety, it is likely that it could be the first vaccine against malaria.

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However, before that can happen, a number of steps need to be followed: First, regulatory authorities have to license the vaccine; the WHO then makes a recommendation for use and prequalifies the vaccine; the Ministries of Health in countries where malaria remains a big problem then decide whether they want to introduce the vaccine for use.

GSK has already submitted a regulatory application for RTS,S to the European Medicines Agency, in June last year. If EMA’s Committee for Medicinal Products for Human Use (CHMP) gives a positive scientific opinion on RTS,S, WHO said ‘a recommendation for use and subsequent prequalification may occur in the course of 2015.’ If all the necessary reviews and approvals are favourable, RTS,S could become available as early as 2016.

The final part of the process will be the availability of money from GAVI, a public-private partnership vaccine alliance, for the procurement of the vaccine for endemic countries.

In the third set of results the efficacy levels of the vaccine were below 50 per cent. Why have they been declining as the research advances and what does this mean in terms of trust levels?

The immune response falls as time goes, and This was the reason for examining the effect of a booster dose. Remember, RTS,S is the first generation malaria vaccine and it will be improved over time. This is only the starting point in fighting malaria with a vaccine.  Remember that if approved, it will be the first vaccine in history against a human parasite and, given the disease burden, RTS,S would prevent millions of cases of malaria.

Developing the vaccine for a complicated disease has been a tremendous effort involving many people over many years, and the results so far have been quite encouraging. We would all like to see a higher efficacy and efforts continue to be made towards that end.

What are the required efficacy levels of a vaccine at the third trial for it to be approved by WHO?

The WHO does not give a definite efficacy level which has to be crossed.  It will depend on factors such as how common the illness is, what other vaccines are available and what the side effects are.

What other interventions exist for malaria control?

In recent years, there has been a lot of effort put into the global fight against malaria, and significant progress has been seen due to the use of interventions like drugs (artemisinin based combination therapies), insecticide treated bed nets and environmental controls. This demonstrates the need for a broad assortment of tools we can use in the fight against malaria. Different tools work better under different settings and conditions.

In addition, a lot of work still remains to be done because of challenges such as emerging drug and insecticide resistance. Additional tools such as malaria vaccines are, therefore, needed and their development has been accelerated in recent years.

Malaria has been deemed as one of the killer diseases, especially in children under five in Africa. Why has it become so difficult to eradicate the disease or reduce it to a minimum?

It was not easy to control polio, for example, and indeed, research continues to this day to improve polio vaccines. The only major infectious disease we’ve been able to eradicate thus far is smallpox, and that was achieved with a vaccine. Malaria is particularly difficult because it is a parasite, with different lifecycles and different species unlike viruses or bacteria.

At present, preventative and treatment strategies are increasingly hampered by the emerging parasite resistance to newly introduced drugs. What is the solution to this if the malaria vaccine is taking too long to be unveiled?

There is no single solution right now to defeating malaria. Malaria parasite resistance to drugs and mosquito resistance to insecticides makes our fight against the disease much more difficult. This is why we need to keep working to improve our drug and insecticide tools and treatment strategies, as well as develop additional tools such as a malaria vaccine.

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