Systematic reviews in malaria: global policies need global reviews

Leveraging innovation technologies to respond to malaria: a systematized literature review of emerging technologies

BACKGROUND

In 2019, an estimated 409,000 people died of malaria and most of them were young children in sub-Saharan Africa. In a bid to combat malaria epidemics, several technological innovations that have contributed significantly to malaria response have been developed across the world. This paper presents a systematized review and identifies key technological innovations that have been developed worldwide targeting different areas of the malaria response, which include surveillance, microplanning, prevention, diagnosis and management.

METHODS

A systematized literature review which involved a structured search of the malaria technological innovations followed by a quantitative and narrative description and synthesis of the innovations was carried out. The malaria technological innovations were electronically retrieved from scientific databases that include PubMed, Google Scholar, Scopus, IEEE and Science Direct. Additional innovations were found across grey sources such as the Google Play Store, Apple App Store and cooperate websites. This was done using keywords pertaining to different malaria response areas combined with the words "innovation or technology" in a search query. The search was conducted between July 2021 and December 2021. Drugs, vaccines, social programmes, and apps in non-English were excluded. The quality of technological innovations included was based on reported impact and an exclusion criterion set by the authors.

RESULTS

Out of over 1000 malaria innovations and programmes, only 650 key malaria technological innovations were considered for further review. There were web-based innovations (34%), mobile-based applications (28%), diagnostic tools and devices (25%), and drone-based technologies (13%.

DISCUSSION AND CONCLUSION

This study was undertaken to unveil impactful and contextually relevant malaria innovations that can be adapted in Africa. This was in response to the existing knowledge gap about the comprehensive technological landscape for malaria response. The paper provides information that countries and key malaria control stakeholders can leverage with regards to adopting some of these technologies as part of the malaria response in their respective countries. The paper has also highlighted key drivers including infrastructural requirements to foster development and scaling up of innovations. In order to stimulate development of innovations in Africa, countries should prioritize investment in infrastructure for information and communication technologies and also drone technologies. These should be accompanied by the right policies and incentive frameworks.

DOPS Adjuvant Confers Enhanced Protection against Malaria for VLP-TRAP Based Vaccines

Vaccination remains the most effective and essential prophylactic tool against infectious diseases. Enormous efforts have been made to develop effective vaccines against malaria but successes remain so far limited. Novel adjuvants may offer a significant advantage in the development of malaria vaccines, in particular if combined with inherently immunogenic platforms, such as virus-like particles (VLP). Dioleoyl phosphatidylserine (DOPS), which is expressed on the outer surface of apoptotic cells, represents a novel adjuvant candidate that may confer significant advantage over existing adjuvants, such as alum. In the current study we assessed the potential of DOPS to serve as an adjuvant in the development of a vaccine against malaria either alone or combined with VLP using Plasmodium falciparum thrombospondin-related adhesive protein (TRAP) as a target antigen. TRAP was chemically coupled to VLPs derived from the cucumber mosaic virus fused to a universal T cell epitope of tetanus toxin (CuMVtt). Mice were immunized with TRAP alone or formulated in alum or DOPS and compared to TRAP coupled to CuMVtt formulated in PBS or DOPS. Induced immune responses, in particular T cell responses, were assessed as the major protective effector cell population induced by TRAP. The protective capacity of the various formulations was assessed using a transgenic Plasmodium berghei expressing PfTRAP. All vaccine formulations using adjuvants and/or VLP increased humoral and T cell immunogenicity for PfTRAP compared to the antigen alone. Display on VLPs, in particular if formulated with DOPS, induced the strongest and most protective immune response. Thus, the combination of VLP with DOPS may harness properties of both immunogenic components and optimally enhance induction of protective immune responses.

Microcrystalline Tyrosine (MCT®): A Depot Adjuvant in Licensed Allergy Immunotherapy Offers New Opportunities in Malaria

Microcrystalline Tyrosine (MCT^®) is a widely used proprietary depot excipient in specific immunotherapy for allergy. In the current study we assessed the potential of MCT to serve as an adjuvant in the development of a vaccine against malaria. To this end, we formulated the circumsporozoite protein (CSP) of P. vivax in MCT and compared the induced immune responses to CSP formulated in PBS or Alum. Both MCT and Alum strongly increased immunogenicity of CSP compared to PBS in both C57BL/6 and BALB/c mice. Challenge studies in mice using a chimeric P. bergei expressing CSP of P. vivax demonstrated clinically improved symptoms of malaria with CSP formulated in both MCT and Alum; protection was, however, more pronounced if CSP was formulated in MCT. Hence, MCT may be an attractive biodegradable adjuvant useful for the development of novel prophylactic vaccines.

Virus-Like Particle (VLP) Plus Microcrystalline Tyrosine (MCT) Adjuvants Enhance Vaccine Efficacy Improving T and B Cell Immunogenicity and Protection against Plasmodium berghei/vivax

Vaccination is the most effective prophylactic tool against infectious diseases. Despite continued efforts to control malaria, the disease still generally represents a significant unmet medical need. Microcrystalline tyrosine (MCT) is a well described depot used in licensed allergy immunotherapy products and in clinical development. However, its proof of concept in prophylactic vaccines has only recently been explored. MCT has never been used in combination with virus-like particles (VLPs), which are considered to be one of the most potent inducers of cellular and humoral immune responses in mice and humans. In the current study we assessed the potential of MCT to serve as an adjuvant in the development of a vaccine against malaria either alone or combined with VLP using Plasmodium vivax thrombospondin-related adhesive protein (TRAP) as a target antigen. We chemically coupled PvTRAP to VLPs derived from the cucumber mosaic virus fused to a universal T-cell epitope of the tetanus toxin (CMVtt), formulated with MCT and compared the induced immune responses to PvTRAP formulated in PBS or Alum. The protective capacity of the various formulations was assessed using Plasmodium berghei expressing PvTRAP. All vaccine formulations using adjuvants and/or VLP increased humoral immunogenicity for PvTRAP compared to the antigen alone. The most proficient responder was the group of mice immunized with the vaccine formulated with PvTRAP-VLP + MCT. The VLP-based vaccine formulated in MCT also induced the strongest T cell response and conferred best protection against challenge with recombinant Plasmodium berghei. Thus, the combination of VLP with MCT may take advantage of the properties of each component and appears to be an alternative biodegradable depot adjuvant for development of novel prophylactic vaccines.

Treatment of African children with severe malaria - towards evidence-informed clinical practice using GRADE

Background

Severe malaria is a major contributor of deaths in African children up to five years of age. One valuable tool to support health workers in the management of diseases is clinical practice guidelines (CPGs) developed using robust methods. A critical assessment of the World Health Organization (WHO) and Kenyan paediatric malaria treatment guidelines with quinine was undertaken, with a focus on the quality of the evidence and transparency of the shift from evidence to recommendations.

Methods

Systematic reviews of the literature were conducted using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) tool to appraise included studies. The findings were used to evaluate the WHO and Kenyan recommendations for the management of severe childhood malaria.

Results

The WHO 2010 malaria guidance on severe malaria in children, which informed the Kenyan guidelines, only evaluated the evidence on one topic on paediatric care using the GRADE tool. Using the GRADE tool, this work explicitly demonstrated that despite the established use of quinine in the management of paediatric cases of severe malaria for decades, low or very low quality evidence of important outcomes, but not critical outcomes such as mortality, have informed national and international guidance on the paediatric quinine dosing, route of administration and adverse effects.

Conclusions

Despite the foreseeable shift to artesunate as the primary drug for treatment of severe childhood malaria, the findings reported here reflect that the particulars of quinine therapeutics for the management of severe malaria in African children have historically been a neglected research priority. This work supports the application of the GRADE tool to make transparent recommendations and to inform advocacy efforts for a greater research focus in priority areas in paediatric care in Africa and other low-income settings.

Alternative visual displays of metaanalysis of malaria treatment trials to facilitate translation of research into policy

Typically, metaanalyses show relative effects and heterogeneity, but not absolute effects-an essential element in policy decision. Data obtained through a systematic review of antimalarial treatment trials and virtual trials were used to generate a display that shows and quantifies absolute and relative effects as well as heterogeneity for comparative trials results. A plot of failure rates (with 95% confidence intervals) of the test drug on the y axis against the risk difference (RD) versus the comparator drug on the x axis is proposed; the area is divided into 4 quadrants by a vertical line (no RD) and a horizontal line (maximum tolerated failures, e.g., 10% for antimalarials). This allows identifying where a drug can be used (meeting efficacy requirements) and quantifying differences (versus another treatment option). The area of the polygon connecting the study points expresses heterogeneity. This graphic display is simple to prepare and interpret and combines in 1 graph both measures of absolute treatment effect and difference, as well as heterogeneity. It may complement current methods and provide useful information in policy decision making.