Towards ending Malaria in the sub-Saharan Africa: Is the RTS, S Malaria Vaccine really a game changer?

Introduction

The WHO declaration of RTS, S malaria vaccine on 6^th October 2021 for extensive use among children in sub-Saharan Africa has been hailed as a “game changer” towards eliminating malaria burden by 90% by 2030.  “This long-awaited malaria vaccine is a breakthrough for science, child health and malaria control,” said WHO director-general Tedros Adhanom Ghebreyesus at a press briefing announcing the endorsement. According to the result of the pilot trial, RTS,S has been proven to significantly reduce life-threatening, severe malaria among children by 30 percent. Therefore, the vaccine appears as a candle in the night as the international community has set ambitious goals for malaria by 2030 and has put RTS,S on the table as a tool to be used in an integrated approach with other malaria interventions.

Global Malaria disease burden

To understand why the RTS, S is considered as the Messiah and comes with so much hope, let’s get back in 2019. The number of malaria cases is estimated at 229 million (M) in 87 malaria-endemic countries and the number of deaths at 409,000, 67% of which are in children under 5. Worldwide, 29 countries affected and Africa with 7 countries carried more than the half of both reported cases and deaths.

Nigeria (27%), the Democratic Republic of Congo (12%), Uganda (5%), Mozambique (4%), and Niger (3%) together accounted for nearly 51% of cases. Nearly 95% of deaths occurred in 31 countries, with Nigeria (23%), Democratic Republic of Congo (11%), Tanzania (5%), Mozambique (4%), Niger (4%), and Burkina Faso (4%) accounting for nearly 51% of deaths.

As this article provides insights into the potential impact of the vaccine we will also review its implementation challenges as leaders across Africa are considering whether and how to deploy the vaccine.

Disease Burden in Africa

About 94% of all malaria cases and deaths in the world today occur in the sub Saharan Africa. This is because the majority of infections in Africa are caused by Plasmodium falciparum, the most dangerous and widespread of the four human malaria parasites in Africa. Despite significant progress with greater use of treated bed nets, indoor residual spraying, rapid diagnostic and the adoption of preventive anti-malaria drugs, malaria remains a primary killer of children in sub-Saharan Africa. More than 260,000 African children die from malaria each year. While malaria deaths have been cut by half since 2000 (Figure 1), the vaccine has come at a time when progress against malaria has stalled or reversed in some areas.

Public health benefits and implementation challenges

The addition of RTS,S/ AS01 vaccine could prevent 30% (77,200) mortality of the children  under 5  with considerable public health benefit and cost-effectiveness especially, endemic regions and in high parasite prevalence areas such as the West and Central Africa (Figure 2). By 2030,  approximately 849,200 lives will be saved attributed to the vaccine and assuming optimal vaccine supply and wider roll out in Africa with all the other malaria control programme remaining constant or scale up too.

According to WHO 20219 vaccine pilot program in children in three African countries – Malawi, Ghana, and Kenya three doses, along with a booster, have a modest efficacy of about 36% in children (age 5–17 months) and about 26% in infants (age 6–12 weeks) against clinical malaria during a 48-month follow-up. However, the efficacy varies among population subgroups and with the parasite strain, it reduces without a booster and offers protection for a limited duration. The 4 staggered doses are likely to pose huge implementation challenges. Firstly it may not be easy to integrate the vaccine with existing vaccination or malaria control programmes; secondly the costs per fully vaccinated child ranged from US$25 (Burkina Faso) to US$37 (Kenya) assuming a vaccine price of US$5 per dose(Sicuri et all 2019). Across countries, recurrent costs represented the largest share dominated by vaccines (including wastage) and supply costs. The delivery of the 4^th doses in outreach settings is likely to increase the costs as African countries roll out to hard to reach areas coupled with unknown vaccine future price; finally the vaccine may face similar challenges associated with Covid 19 vaccines roll out in Africa especially on population hesitancy and consistent supply to ensure availability in high transmission and hard to reach areas.

Conclusion

The analysis has demonstrated that the RTS,S vaccine can prevent and lower overall mortality rate in sub-Saharan Africa when used as a prevention strategy for the  eradication of Malaria.  However, the vaccine has modest efficacy and its effectiveness depends on multiple factors. In order to increase its efficacy against the P. falciparum, there is need for multiple doses that may occur outside the normal integrated vaccination programmes. The deployment of the vaccine however, should be integrated with other existing malaria control programs such as use of treated bed nets, rapid diagnostics, and anti-malaria drugs. The African countries can learn from the challenges faced in rolling out the covid-19 vaccination programme in Africa and how best to advocate for continuous supply of vaccine and increase uptake of the vaccine prioritizing high transmission areas in resource constraint environment.

Tapson Ndundu

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