Malaria in the future with Effective Vaccine(s)?

Graph Source: Our World In Data
By Dr. Derick Pasternak, Malaria Science & Research Coordinator, Malaria Partners International 

Readers of The Economist’s March 19 Edition noted a very optimistic looking chart on the next to the last page (1), where this international political/economic/cultural weekly always displays a graphic representation of a trend the editors discern in world affairs.  The chart, which represents actual and projected malaria mortality between 2000 and 2050, takes into account the development and optimal distribution of malaria vaccines, some deployed already and others in the pipeline.

Malaria deaths, which are highly concentrated in sub-Saharan Africa, had fallen steadily between 2000 and 2019, but rose slightly since then, presumably because of the diversion of resources to combat the COVID-19 pandemic.  The projection envisions a dramatic drop starting almost immediately, resulting in a 75% decrease in total mortality by 2030 as compared to what it would be at today’s rates, taking into account the growth in population.  Then the rate is projected to remain proportional to the population. True to its title, The Economist also asserts that this decrease in mortality is not only a humanitarian gain but one that will result in improved productivity of these societies since the lives saved will be mostly those of children, who will grow into productive adults.

It is quite likely that The Economist’s chart and the accompanying short article came as a follow-up to the WHO’s release of two publications on March 4 (2,3), in which WHO gave notice of its modified guidelines that included the use of the RTS,S/AS01 vaccine.  Still, the information in the article may be somewhat misleading, in that it describes the vaccine as requiring “four doses, [being] hard to manufacture and [reducing] severe infections by a mere 30%…”  In fact, several published articles within the past two years quoted efficacy rates of this vaccine between 26% (4) and 58% (5).  Further, another article reported modifying the third dose of the same vaccine and achieving 87% percent efficacy without a fourth dose (6).  To be sure, this last result has not been confirmed in repeat publications yet.

The article is correct in referring to a “jab developed by scientists at Oxford [that] has shown 77% effectiveness.” This is the R21 vaccine (7). As well, it takes cognizance of the several other preventive and therapeutic advances that promise significant gains in the struggle against this disease.  The estimate referred to above, which was apparently developed by modelers at the London School of Hygiene and Tropical Medicine (8), seems reasonable, if somewhat frustrating, given that it is still eight years in the future.

References:

1. Graphic Detail Malaria, Another vaccine victory? The Economist, 19 Mar 2022; 442(9288):81.
2. First-ever malaria vaccine recommendation now published in a position paper and in the WHO guidelines for malaria, WHO, 2022 Mar 4; https://www.who.int/news/item/04-03-2022-first-ever-malaria-vaccine-recommendation-now-published-in-a-position-paper-and-in-the-who-guidelines-for-malaria, downloaded 25 Mar 2022.
3. Malaria vaccine: WHO position paper March 2022, Weekly Epidemiological Record No 9., 2022, 97:61-80. https://www.who.int/publications/i/item/WER9709, downloaded 25 Mar 2022.
4. Arora N, Anbalagan LC, Pannu AH, Towards Eradication of Malaria: Is the WHO’s RTS,S/AS01 Vaccination Effective Enough? Risk Manag Healthc Policy, 2021 Mar 12;14:1033-1039.
5. Bell GJ, Loop MS, Mvalo T, & al., Environmental Modifiers of RTS,S/AS01 Malaria Vaccine Efficacy in Lilongwe, Malawi, BMC Public Health, 2020 Jun 12;20(1):910. doi: 10.1186/s12889-020-09039-z.
6. Das J, Fallon JK, Yu TC & al., Delayed Fractional Dosing With RTS,S/AS01 Improves Humoral Immunity to Malaria Via a Balance of Polyfunctional NANP6- and Pf16-Specific Antibodies. 2021 Nov 12; 2:1269-1286. https://www.cell.com/med/fulltext/S2666-6340(21)00343-3.
7. Datoo MS, Natama MH, Somé A & al., Efficacy of a Low-Dose Candidate Malaria Vaccine, R21 in Adjuvant Matrix-M, with Seasonal Administration to Children in Burkina Faso: A Randomised Controlled Trial, Lancet 2021 May 15;397(10287):1809-1818. doi: 10.1016/S0140-6736(21)00943-0.
8. Severe malaria among young African children dramatically reduced through seasonal vaccination and preventative drug combination, London School of Hygiene and Tropical Medicine, 2021 Aug 26; https://www.lshtm.ac.uk/newsevents/news/2021/severe-malaria-among-young-african-children-dramatically-reduced-through downloaded 26 Mar 2022.