Impact of new malaria vaccine to Reduce child mortality in malaria-endemic regions of the World.

By

Maleeha Nasir (Intern from University of California Santa Cruz)

Abstract

The parasite plasmodium, which causes malaria, is spread through the bite of infected mosquitoes. Malaria continues to be a major worldwide health burden, particularly for children living in areas where the disease is endemic. In order to lessen the devasting effects of this illness, it has long been a priority to create an effective malaria vaccine RTS, S/AS01. The potential influence of a novel malaria vaccine on lowering child mortality in malaria-endemic areas worldwide is addressed in this abstract. Especially in sub-Saharan Africa, malaria continues to be a major cause of morbidity and mortality in children under the age of five. Although some existing preventive and treatment measures, such as insecticide-treated bed nets and antimalarial medications, have had some effectiveness, they are insufficient to stop the disease’s spread. The impact of a development of a malaria vaccine that is effective has the potential to significantly lower child mortality rates and lessen the burden on affected populations. A huge advancement in the fight against malaria has been made with the creation of the new malaria vaccine. Large-scale clinical trials have shown the vaccine’s effectiveness, with encouraging findings in terms of lowering the frequency of both clinical malaria and cases of severe malaria in children.

Keywords: Malaria, children, endemic regions, RTS, S/AS01 vaccine, Plasmodium, development, prevention.

Contents

1. Introduction with emphasis on child mortality from malaria.
2. Research finding from field trials of vaccine.
3. Proposed vaccination regime and availability of Vaccine.
4. Discussion.
5. Conclusion.
6. References.

Introduction with an emphasis on child mortality from malaria

Infection with a protozoan parasite of the genus of the order Haemosporida in the phylum Apicomplexa causes malaria, the most significant parasitic illness of humans. Malaria is characterized by a cluster of symptoms including high body temperature, shivering, headache, diarrhea, nausea, vomiting, pain in the muscles and joints, and rapid breathing and heart rate. The mortality and morbidity rates from Plasmodium falciparum malaria continue to be the highest of any malarial species. Up to 87% of people in endemic regions get infected with no outward signs of illness. With varying degrees of success, attempts have been conducted over the past century to control, decrease, and eventually eradicate the effects of malaria, particularly in tropical and subtropical Africa and some regions of Asia. Over the last two decades, researchers have made significant strides toward creating a malaria vaccine ¹.

As of 2021, the global incidence of malaria has been estimated to have reached a total of 247 million cases across 84 nations where the disease remains endemic. This represents an increase of 2 million cases when compared to the previous year. It is imperative to note that the continued presence of malaria in these regions highlights the ongoing need for effective prevention and treatment measures to combat the spread of this debilitating illness. The African region accounts for about 95% of cases and 96% of deaths globally due to malaria. Approximately 80% of all deaths due to malaria in Africa occurred among children under the age of 5 years in 2021 ¹.  Four African countries accounted for just over half of all malaria deaths worldwide: Nigeria (31.3%), the Democratic Republic of the Congo (12.6%), United Republic of Tanzania (4.1%) and Niger (3.9%) ⁵. Although this mortality is alarming, it has relatively decreased from the 91% it was back in 2000.

The RTS, S vaccine, also known as Mosquirix, is a pioneering development in the fight against malaria. It is the first and currently the only vaccine that has been demonstrated to significantly reduce the occurrence of malaria in children, including severe cases, hospital admissions, and the need for blood transfusions. The vaccine is currently being implemented in areas where malaria transmission is moderate to high and is responsible for a significant proportion of childhood visits to healthcare facilities, often accounting for up to 60% ¹.

Research findings from field trials of the vaccine

Futhermore the research findings found from field trials of the vaccine is several malaria vaccine candidates have been developed and are being evaluated in several African research institutions. Among these RTS, S is leading the study for which the most significant Phase 3 trial of malaria vaccine trial involving 15,500 infants and young children is underway in 11 research centers in seven African countries. In the Phase 3 trial, the vaccine was generally well tolerated, with adverse reactions similar to those of other childhood vaccines. Among children in the older age group, there was an increased risk of febrile seizures within 7 days after any of the vaccine doses. Among the younger infants, this risk was only apparent after the fourth dose. There were no long-lasting consequences due to any of the febrile seizures.

Among children aged 5–17 months who received three doses of RTS,S administered at 1-month intervals, followed by a fourth dose 18 months later, the vaccine reduced malaria by 39%, equivalent to preventing nearly 4 in 10 malaria cases. In addition, the 4-dose vaccine schedule reduced severe malaria by 31.5% in this age group, with reductions also seen in malaria hospitalizations, all-cause hospitalizations and the need for blood transfusions. Among children aged 5–17 months who did not receive a fourth dose of the vaccine, the protective benefit against severe malaria was lost, highlighting the importance of the fourth dose of this vaccine to maximise its benefits ⁶.

Table 1

At present, RTS, S currently reached the final phase of the trial and gives satisfactory results. The initial results of phase III RTS,S/AS01 which is the intervention given to larger numbers of the target group of people to confirm it works (i.e. the efficacy of the intervention), monitor side effects, compare it to commonly used treatments, and collect information that will allow the drug or treatment to be used safely,  have reduced severe malaria by approximately 50% in the older age group of 5 to 17 months and 36.6% in young children (6–12 weeks). These clinical trials will deliver some new treatment options to fight against this disease ². My research indicates that RTS,S has been an effective vaccination in preventing malaria in children. It has reached phase III and is currently in phase IV, and several research investigations have produced diverse data on its success rate.

Current research and development efforts to develop malaria vaccines are primarily directed toward reducing the morbidity and mortality associated with malaria caused by Plasmodium falciparum. Malaria Vaccine Roadmap had a strategic goal of creating a vaccine with 80% protective efficacy against P. falciparum by 2020. However, the malaria vaccines will also need to have an impact on malaria transmission for global elimination of the disease. Hence, the strategies should focus on developing vaccines that can be used with other malaria control interventions to interrupt malaria transmission and eradicate this disease. Moreover, vaccine development efforts need also to pay attention to other Plasmodium species along with P. falciparum, especially Plasmodium vivax, for complete eradication.

Proposed vaccination regime and availability of Vaccine

Availability of Vaccine and other interventions

Since 2019, the vaccine, known as The RTS,S/AS01, has been administered to more than 1.7 million children in areas of Ghana, Kenya and Malawi as part of a pilot program to demonstrate its safety and efficacy. Starting in early 2024, the vaccination campaign will expand across those three nations, and will also be introduced for the first time into routine immunization programs in Benin, Burkina Faso, Burundi, Cameroon, Democratic Republic of the Congo, Liberia, Niger, Sierra Leone and Uganda. At least 28 African nations have expressed interest in receiving the vaccine. The rollout plan for 2023-2025 is part of a framework for allocation designed to prioritize areas where the risk of malaria illness and death among children are the highest.

To develop that framework, and to help ensure equitable distribution while supplies remained limited, WHO convened a panel of experts in 2022 that included representatives from UNICEF, WHO and the Gavi Secretariat, civil society and Africa-based NGOs like the Africa Centers for Disease Control and Prevention, or Africa CDC. UNICEF continues to support the distribution of anti-malaria bednets as a key intervention. UNICEF’s supply division buys long-lasting insecticidal nets, or LLINs, which are more effective than untreated mosquito nets because they are produced with netting treated with a WHO-recommended insecticide, adding a chemical barrier to the physical one, which lasts for up to three years or 20 washings. The percentage of children sleeping under insecticide-treated nets in sub-Saharan Africa increased from less than 40 % in 2011 to over 50% in 2021. Studies have shown that malaria can increase the incidence and severity of malnutrition. Malnutrition, in turn, can increase the risk of complications from malaria, though the evidence is mixed on whether malnutrition affects the risk of malaria infection ³.

Proposed vaccination regime

The vaccine requires three doses administered between the ages of 17 months and 5 years, and a fourth dose roughly 18 months later. Strategic Advisory Group of Experts on Immunization (SAGE), and Malaria Policy Advisory Group (MPAG) recommended for broader use of RTS,S vaccine should be provided in a schedule of 4 doses in children from the age of 5 months to reduce the burden of malaria. Countries may consider providing the RTS,S/AS01 vaccine seasonally, with a 5-dose strategy in areas with highly seasonal malaria or areas with perennial malaria transmission with seasonal peaks ⁴.

Discussion

Overall, the results of the research on the malaria vaccine suggest improved protection against malaria in children.The initial results of phase III, RTS, S/AS01, have reduced severe malaria by approximately 50% in the older age group of 5 to 17 months and 36.6% in young children. Further preclinical evaluations are underway to look into Malaria transmission blocking vaccine candidates Pfs25-EPA and Pfs230D1-EPA for ASO1 which target sexual stage development of Plasmodium falciparum parasites in the mosquito host, there by reducing mosquito infectivity ⁷. The further development of a RTS,S malaria vaccine may result in a larger variety of health advantages.

The proposed vaccine has an acceptable degree of effectiveness in preventing malaria and lowering the severity of infections in children. Further research is necessary, nevertheless, to determine its long-term effectiveness and durability of protection. Comparisons with alternative interventions highlight the vaccine’s advantages. Discussions of challenges with distribution and availability highlight the significance of sustainability. Enhancing vaccine effectiveness and durability, examining age-specific immunization, looking into combination techniques, addressing delivery and access challenges, encouraging vaccine uptake, evaluating cost-effectiveness, and setting up surveillance systems are some future possibilities. The objective is to produce more potent, widely available, and long-lasting malaria vaccinations that can considerably lessen the impact of malaria on children in endemic places around the world.

Conclusion

The widespread availability of the new malaria vaccine in endemic areas where the disease is prevalent has the potential to have a number of profound effects. First, extensive immunization efforts can significantly lower rates of child mortality due to malaria. The vaccine could save countless lives by preventing malaria infections or lessening their severity and contribute to meeting the world’s goals for child survival.

In conclusion, the impact of a new malaria vaccine’s accessibility and broad use have the potential to drastically lower the rate of child death in areas of the world where malaria is endemic. The vaccine can save lives, lessen the strain on healthcare systems, and aid in general socioeconomic development by preventing and controlling malaria infections. Realizing these advantages and making significant strides in the global fight against malaria need ongoing research, international cooperation, and continuous investments in the development and use of malaria vaccines.

Works Cited

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