Dr M Adam Ali
Health Education England Fellow in Medical Education at MedShr
More than 1 million doses of the RTS,S/AS01 malaria vaccine have been administered so far in high incidence regions of Sub-Saharan Africa.
Vaccines are one of the most cost-effective interventions to reduce childhood mortality in low- and middle-income countries (LMICs).
The World Health Organisation (WHO) has an Expanded Programme on Immunisation (EPI) programmes, which operates in 73 countries to vaccinate over 700 million children against major infectious diseases.
Benefits of vaccination programmes
The data supporting the effectiveness of vaccination programmes in preserving life is significant: it is estimated that vaccines delivered between 2001 and 2020 will avert more than 20 million deaths.
The majority of these are in children under 5 years of age. A recent WHO bulletin discusses that there can be a disproportionate focus on minor vaccine safety issues, and that the vast benefits are often overlooked.
Despite this, some of these benefits and successes include: eradication of smallpox and certain strains of poliovirus; elimination of measles, mumps and rubella in Finland; prevention of infection such as the Hepatitis A vaccine; and various other socio-economic and political benefits, such as allowing safer and more free travel, protection against bioterrorism and empowering women1.
Malaria is estimated to have caused over 400,000 deaths in 2018, with 94% of these deaths occurring in sub-Saharan Africa
Why is the malaria vaccination trial targeted towards Africa?
Malaria is estimated to have caused over 400,000 deaths in 2018, with 94% of these deaths occurring in sub-Saharan Africa and the majority, approximately 7 in 10 deaths, being in children under 5 years of age.
In these areas, as much as 60% of childhood outpatient healthcare visits are due to malaria. Malaria claims the life of one child every 2 minutes.
Prioritisation of areas with highest incidence of malaria could have the greatest impact on reducing the burden of disease.
Malaria vaccination programmes in Africa
Despite significant progress in the fight against malaria in the past decade, data from 2017 suggest that the decline in mortality is plateauing.
RTS,S/AS01 is the name of the first vaccine targeting Plasmodium falciparum, the parasite which causes malaria.
It had shown a protective effect of approximately 36% in young children in a late-stage clinical trial from 2014, reducing cases of severe malaria, hospital admissions and the need for blood transfusions.
However, there have been concerns regarding potential safety from initial trials, lack of evidence of actual impact on deaths, and questions about the feasibility of delivery of the 4-dose schedule (5, 6, 7, and 25 months).
For this reason, in 2015, WHO recommended pilot implementation in order to resolve safety concerns and to establish sustained effectiveness, including impact on malaria hospitalisations and mortality.
The Malaria Vaccine Implementation Programme (MVIP) began in 2019, set up to pilot introductions in Ghana, Kenya, and Malawi.
Some 360,000 children were to be vaccinated each year over a 4-year period, and more than 1 million doses of the RTS,S/AS01 malaria vaccine have been administered in the time of the programme thus far.
MVIP Results to Date
One year on, about 275,000 children have received their first dose of the RTS,S malaria vaccine through the programme.
Kenya, for example, has seen a 40% additional reduction in malaria cases achieved through vaccination. This is an addition to the scale up of proven interventions, such as insecticide-treated bednets.
What challenges remain?
One of the challenges identified with implementing the vaccine has been the need for a fourth dose given 18 months post dose 3.
In some countries, this may necessitate a new vaccine contact point. If coverage of this fourth dose is reasonable, then in many countries it could be as efficient to introduce a 3-dose schedule, which would enable vaccine supply to a larger number of children.
This uncertainty requires further research. Differences on the public health and cost benefit of different approaches should be informed by data from the pilot countries in the coming years.
Furthermore, during any initial expansion it is likely that vaccine supply will be limited as manufacturing capability is scaled up.
Subnational introduction to highest priority areas could provide an equitable means to scale up distribution.
We invite healthcare professional to join the Public Health Discussion Group on MedShr to discuss vaccination programmes and their challenges: medshr.it/publichealth
1. Hogan AB, Winskill P, Ghani AC. Estimated impact of RTS,S/AS01 malaria vaccine allocation strategies in sub-Saharan Africa: A modelling study. PLoS Med. 2020 Nov 30;17(11):e1003377. doi: 10.1371/journal.pmed.1003377. PMID: 33253211.
Vaccination greatly reduces disease, disability, death and inequity worldwide. FE Andre et al. Accessed online at https://www.who.int/bulletin/volumes/86/2/07-040089/en/