Mary Grace Nimmer
Following recent years of stagnation in the decades-long fight against malaria, the World Health Organization (WHO) has made a breakthrough recommendation. On October 6, 2021, two WHO global advisory bodies, one for immunization and one for malaria, provided a joint endorsement for the widespread use of the world’s first malaria vaccine in sub-Saharan Africa and in other regions with moderate to high transmission of Plasmodium falciparum malaria. This represents the culmination of 30 years of vaccine research. The RTS,S/AS01 (RTS,S) vaccine–not only the first of its kind for malaria, but the first for any parasitic disease–is not a silver bullet for the illness that takes hundreds of thousands of lives annually, but it could be the difference between life and death for thousands of susceptible children and adults alike.
Malaria is a parasitic infection most commonly transmitted between individuals by a mosquito vector. Its first symptoms begin within two weeks of the infecting mosquito bite, and if left untreated, severe illness and death can occur within 24 hours. The World Health Organization reports over 220 million cases of malaria annually, with Africa accounting for over 90% of cases worldwide. Children under age five are among the most vulnerable to malaria and account for the majority of malaria deaths. For survivors, there can be lifelong complications associated with an impaired immune system, organ damage, and cognitive delays. What makes this parasite particularly virulent is its ability to reinfect an individual repeatedly. In parts of sub-Saharan Africa, it is not uncommon for children to be infected multiple times in one year. Currently, the most widespread preventative measure is the use of insecticide-treated bed nets, though they have shown only a 20% reduction in childhood deaths.
In a four dose regimen, the vaccine primes a child’s immune system to kill the parasite before illness sets in, protecting the child from developing severe malaria and interrupting the human-mosquito-human cycle that makes the disease especially prolific in close-quarter households and communities. The first three doses are given monthly between five and seven months of age; the fourth dose, a booster, is given at 18 months.
The four dose series required by the RTS,S vaccine raises concerns of feasibility, especially in developing countries where healthcare infrastructure and accessibility are considerably lacking. In response, the WHO designed a two year pilot program to gather data on the vaccine’s feasibility, impact, and safety in real-life settings. The WHO Malaria Vaccine Implementation Programme, which began in 2019 and was conducted in regions of Kenya, Ghana, and Malawi by their respective Ministries of Health, called for unprecedented cooperation between key funding and administrative partners worldwide. Through the coordinated efforts of the countries’ public health, religious, and political leaders, as well as global stakeholders and local healthcare workers, the pilot program produced evidence of a strong safety profile, distribution feasibility, and cost effectiveness.
From the beginning of the program, the communities not only demonstrated acceptance of the vaccine, but created a high demand for it as well. More importantly, the program found that the families were motivated to bring their children in for all four doses and were capable of doing so. Moreover, while insecticide-treated bed nets required the development of a new production and distribution system, existing public health education and childhood immunization systems proved to be adequate frameworks for the distribution of the vaccine. The pilot program also showed compelling evidence that the vaccine increased equity in malaria prevention by reaching children who were otherwise unprotected from the disease. The program, however, was not without its challenges. Natural disasters, healthcare worker strikes, and COVID-19 shutdowns threatened the program’s efforts; yet, even in the midst of a pandemic that interrupted healthcare delivery, the WHO reported successful distribution of the vaccine.
With an efficacy rate of only 30%, a number that decreases even further if doses are missed, the RTS,S vaccine alone is not an answer to decades of anti-malaria efforts, but it is a significant step in reducing inequities in malaria protection. Used in combination with insecticide-treated bednets and anti-malarial drugs, this vaccine has the potential to “save tens of thousands of young lives every year,” according to WHO Director-General Dr. Tedros Adhanom Ghebreyesus. A modelling study published in November 2020 predicts that the vaccine has the potential to prevent 5.4 million cases and 23,000 deaths in children under age five annually.
With the promise of advancing global health, the future of the malaria vaccination effort now lies in the hands of the international community. Broader rollouts and country-specific decisions on adopting the vaccine are dependent on funding. Gavi, the Global Vaccine Alliance, is a leading authority on the matter, and whether or not the Alliance will approve funding is still unclear. With international attention and resources diverted to the pandemic response, the vaccine, if approved, could take well over a year to be implemented on a large scale, but despite the treatment’s uncertain future, this long-awaited vaccine has sparked momentum in the global anti-malaria effort and could save thousands of lives worldwide.