Malaria could become the second human disease to be wiped out: how it could be achieved

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The approval of the new RTS,S/AS01 malaria vaccine by the WHO is encouraging news, especially at a time when the world is more aware than ever of the pain that diseases can bring.

In fact, there is a special circumstance, and that is that Malaria is one of the diseases that the international organization considers possibly eradicable. If this milestone were achieved, it would become the second human disease to be eliminated, after smallpox. However, the vaccine alone will not be able to eradicate malaria, but must be accompanied by many other actions.

To understand how malaria could be eradicated, it is necessary to understand why it is a candidate for eradication, bearing in mind that this possibility does not exist for all diseases (e.g., COVID-19 is not considered eradicable by current means).

Malaria is an infection caused by a family of pathogens called Plasmodium. These protozoa have a complex life cycle, with two other participants: a vector, which are the females of about 60 species of mosquitoes of the genus Anopheles, and a host, which is the human being (the only exception is the species P. malariae, which in addition to humans can infect dogs).

In short, these small parasites need humans to feed and reproduce, and use mosquitoes to travel from an infected human to a healthy one. The key to fighting malaria is to intervene in that cycle.

The recent approval of this vaccine, and its administration to children in their early stages of life, is one more tool to prevent the disease, but the efficacy of this vaccine is between 30 and 40% at best. With these results, it is clearly unlikely to achieve the goal of eradication on its own, but it is an important preventive tool. If administered in a four-dose schedule to children from five months of age, it could prevent hundreds of thousands of deaths in that age group, although it has the handicap of the high number of doses in the schedule, something that in malaria-endemic countries with weak health systems makes its implementation complicated.

Insecticides are used in vector control: larvicides in aquatic breeding sites or adulticides used in impregnation of surfaces such as the walls of houses or resting and biting areas. Physical barriers, such as insecticide-impregnated bed nets, are used to block biting by female anopheles to prevent them from biting during the hours of activity, since these mosquitoes are nocturnal.

Putting all this into practice is costly and complex, especially in the current context because the ravages of the COVID-19 pandemic must first be repaired in low-income countries, where three major challenges (HIV/AIDS, malaria and tuberculosis) have seen spikes and higher mortalities.
Re-establishing, stabilizing and sustaining these control and elimination measures will be critical to eliminating malaria.

It is very difficult to estimate dates for malaria eradication. It will depend on innovative solutions that will be essential; and the effectiveness (ability to protect against the disease when applied in real conditions of daily clinical practice or public health programs) of the newly approved vaccine along with others that may be developed will have to be seen. However, the deadlines proposed by the WHO (a reduction in incidence and mortality of at least 90% by 2030) are possible for the time being, but very much conditional on the development of universal coverage in endemic countries and, above all, on their economic development.

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