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mRNA vaccine in development for malaria – too soon for hype?

BioNTech gained prominent public attention for its collaboration with Pfizer which produced a COVID-19 vaccine using mRNA technology. They have once again hit the headlines – this time setting their sights on malaria.

BioNTech’s malaria project is part of the ‘eradicateMalaria’ initiative, led by the kENUP Foundation, to accelerate the eradication of the mosquito-borne disease. The efforts are supported by the World Health Organization (WHO) and the Africa Centers for Disease Control and Prevention (Africa CDC).

mRNA technology has shown huge levels of promise since the onset of the COVID-19 pandemic, with both Pfizer-BioNTech and Moderna using the technology to put vaccines on the market at an unprecedented pace. Malaria, however, is an altogether different phenomenon. Decades of research into the matter failed to put out an effective vaccine.

Despite the long decades of research failing yield results, media headlines appear optimistic regarding the announcement. BioNTech also appears to be optimistic regarding the vaccine, with plans of beginning clinical testing by the end of 2022. mRNA vaccines, due to the technology they implement, can allow for rapid creation of new vaccines. However, malaria is a complex disease to tackle, making the optimistic headlines seem premature.

Malaria is considered one of the deadliest mosquito-borne diseases in India. Image credit: Mr.Smith Chetanachan / 123rf

The technology

This is not to say the technology behind the mRNA vaccines is lacking. In many ways it could offer the means to create innumerable additional vaccines for a range of conditions due to the unique mechanism behind them.

mRNA vaccines differ from conventional vaccines in that they are entirely synthetic. Whereas a typical vaccine will use a weakened or dead strain of a disease to allow recognition within the body’s immune system, mRNA vaccines do not use any pathogenic material. Instead, mRNA vaccines operate by teaching cells within our body to produce a protein, or even part of a protein, which will trigger an immune response should the body ever be exposed to the real pathogen.

A critical difference between mRNA vaccines and conventional vaccines is the development time. As seen by the COVID-19 vaccines produced by Pfizer-BoiNTech and Moderna, the development cycle has been rapid enough to set new records. According to a Harvard Health Blog 

“Just eleven months after the discovery of the SARS-CoV-2 virus [severe acute respiratory syndrome coronavirus 2, the novel coronavirus which causes COVID-19], regulators in the United Kingdom and the US confirmed that an mRNA vaccine for COVID-19 is effective and safely tolerated, paving the path to widespread immunisation. Previously, no new vaccine had been developed in less than four years.”

Modern genome mapping technology can allow rapid development of an mRNA vaccine in response to sudden outbreaks or mutations within a pathogen. Providing the genome has been mapped and the antigens of the pathogen are understood, an mRNA script can be generated. According to Pfizer, this process could take as little as a week to complete.

Given the lack of need for vast stockpiles of pathogenic material, and the ease of production should facilities be made more widely available, mRNA vaccines could open the way for a far more rapid and specific response to emerging threats. This may allow for experience gained from the COVID-19 pandemic to be redirected towards previously existing threats.

BioNTech are suggesting they are ready to take full advantage of the comparable lack of stockpiling to move production into Africa, hoping to produce the malaria vaccines where they are needed most. This would involve co-locating its African manufacturing capabilities with the technology transfer hubs under development by the WHO, in alignment with the African manufacturing strategy created by the Africa CDC.

Such a decision could hugely benefit the continent in addressing the issue of malaria. However, this hinges on the assumption that the vaccine is effective which, given the patchy track record of malaria vaccines, is an uncertainty at the current time.

A rocky history of malaria research

While there are promising candidates in the pipeline, creation of a vaccine for malaria has been a rocky process. Currently, only one vaccine has been approved for use. The limited efficacy of the vaccine underlines the difficulty of the vaccine creation endeavour. 

The world’s first and only licensed malaria vaccine, Mosquirix, was developed by GlaxoSmithKline. The vaccine was the product of many years of clinical trials across several African countries, but is only around thirty percent effective. Safety concerns also marred the rollout of the vaccine, with the largest trial revealing that children who received Mosquirix had a risk of meningitis ten times higher than those who received a control vaccine. The pilot of the vaccine, across Ghana, Kenya and Malawi was struck with difficulty in its delivery due to a lack of digital medical records.

The process of creating a vaccine has taken decades, much of this has been due to the sheer complexity of creating preventative treatments for a parasite, rather than a virus or bacteria. Given the multiple stages of the life cycle of the parasite, creation of a specific antigen target has been difficult. As explained by

“The malaria parasite is a challenging target for a vaccine. It has a complex life cycle that begins when an infected female mosquito bites a human and spits Plasmodium cells called sporozoites into the bloodstream. They multiply in the liver, emerge as another cell type named merozoites, invade red blood cells, and continue to multiply. The blood cells burst, causing fever, headache, chills, muscle aches, and often anemia. (They also flood the blood with gametocytes—the parasite’s reproductive cells—ready to be picked up by the next mosquito.) Along the way, the parasite frequently changes its surface proteins. That makes it an elusive target for the immune system, and for a vaccine.” 

More encouraging news was unveiled earlier this year, with a clinical trial of another vaccine candidate announcing an efficacy of 77 percent. When trialled in 450 children in Burkina Faso, the vaccine was found to be safe, and showed “high-level efficacy” over 12 months of follow-up. Currently the trials are being scaled up to analyse several thousand children across a number of African countries.

Cautious optimism may therefore be warranted, that despite years of struggle to establish any vaccine at all, new candidates are being field tested, showing promising results, while other companies are throwing in their lot to develop further vaccines. However, given the lacklustre results of the past, caution is warranted regarding reporting on the topic.

Success with COVID-19, will it translate to malaria?

A key driver of the suggestion to use mRNA vaccines against malaria has been the success stories against COVID-19. mRNA vaccines have been among the top candidates in the market against the COVID-19 pandemic, with both currently used mRNA vaccines having efficacies noted to be higher than ninety percent in clinical trials. “The response to the pandemic has shown that science and innovation can transform people’s lives when all key stakeholders work together towards a common goal,” said BioNTech Chief Executive and co-founder Professor Ugur Sahin.

The concept of the technology allows for any pathogen that has had its genome mapped to be analysed for potential antigens, which could then be added to an mRNA strand to make a vaccine. However, this approach is far more difficult in the case of malaria. While the spike protein used in the COVID-19 vaccines has been successfully vaccinated against — though, evidence is emerging that the Delta strain is evading the immune response granted by the vaccines — the malaria parasite has multiple stages, each with differing antigens.

Jumping the gun?

While the success of COVID-19 vaccinations is a cause for celebration, it is far too early to suggest that success in this area could mean a similar malaria vaccine is on the horizon. “Together with our partners, we will do whatever it takes to develop a safe and effective mRNA-based malaria vaccine that will prevent the disease, reduce mortality and ensure a sustainable solution for the African continent and other regions affected by this disease,” added Sahin.

While at this stage, before clinical trials have even begun, it is far too soon to jump to  unwarranted optimism, pessimism on the topic may also be too soon a call. Malaria is a serious condition, one that takes the lives of more than 400,000 a year, many of them babies and young children. 

Despite decades of malaria vaccine research amounting to very little, companies are still throwing their weight behind new vaccines and treatments. Such a situation does not hold true in other disease areas. Alzheimer’s disease, a degenerative mental condition correlated with age has no current treatment, with few medications that even slow the onset. Decades of research amounted to little, and this saw numerous companies simply close down their research departments in the area. For malaria to avoid such a catastrophic outcome is itself cause for optimism.

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