Page 55 - Bulletin, Vol.81 No.1, May 2022

For a long time, the prospective of a vaccine against paludism seemed inaccessible. In
total, more than 100 trial vaccines have been tested on humans against Plasmodium
falciparum which is the most harmful parasite of this disease. Until now, there have
been no convincing results.

In fact, it is a vaccine against the parasite, a complex organism with more than 5,000
genes to take into consideration compared to dozens for a virus. It is, therefore, more
complicated to find the right targets in order to develop an effective vaccine.

The vaccine that has been developed by GlaxoSmithKline (GSK) is the Mosquirix or
RTS.S. Scientists have been working on this vaccine since 1987 – more than 30 years.
Since 2019, the Mosquirix has been part of a pilot project: more than 2.3 million doses
have been administered to children in Ghana, Kenya and Malawi. The results have
shown that it reduces by 30% the more serious forms of paludism.

The phase 3 clinical trials have shown that if four doses of the vaccine are administered,
it prevents four cases out of ten of paludism and three cases out of ten of life-
threatening paludism. This is, therefore, the only vaccine that has demonstrated a
certain effectiveness.
This vaccine will not be the key to eradicating paludism but a new tool which can be
added to the preventive treatments (artemisinin, chloroquine, etc.) and the repellent
treatments already available in the anti-paludism stocks especially as there is more
resistance to current medicaments. A combination of the vaccine and the preventive
treatment could reduce hospitalisations and deaths.

A step towards more effective vaccines?

In parallel, other vaccines are giving hope to scientists. One of them, the R21/Matrix M,
developed by Oxford University, has demonstrated very promising results following
phase II with an effectiveness of 77%. The third phase, on 5,000 children, has begun in
Kenya, Tanzania, Burkina Faso and Mali. Results are expected in 2023.

In July, the laboratory, BioNTech had indicated that it would like to launch new trials for
a vaccine using the ARN messenger developed in the wake of Covid-19 vaccines.

Logistical limitations
Before the RTS.S vaccine can be deployed on a massive scale, there are a number of
logistical challenges to be faced. The first one is the financing of these vaccines.

It is necessary to remove patents in order to permit production in the countries
concerned and their deployment at minimum cost so as to administer them free of
charge. Paludism affects essentially the most vulnerable children who live in a state of
extreme poverty. It is vital that they can benefit from this new vaccine.

We must, therefore, rapidly tackle the question of resources: who will finance this?

The question of access to care must also be dealt with. This disease affects a high
number of the refugee populations and nomads. How can one ensure that these
children are able to benefit from the required four doses?

AAFI-AFICS BULLETIN, Vol. 81 No.1, 2022-05 53