Analysis of the potential for a malaria vaccine to reduce gaps in malaria intervention coverage

Background The RTS,S/AS01 malaria vaccine is currently being evaluated in a cluster-randomized pilot implementation programme in three African countries. This study seeks to identify whether vaccination could reach additional children who are at risk from malaria but do not currently have access to, or use, core malaria interventions. Methods Using data from household surveys, the overlap between malaria intervention coverage and childhood vaccination (diphtheria-tetanus-pertussis dose 3, DTP3) uptake in 20 African countries with at least one first administrative level unit with Plasmodium falciparum parasite prevalence greater than 10% was calculated. Multilevel logistic regression was used to explore patterns of overlap by demographic and socioeconomic variables. The public health impact of delivering RTS,S/AS01 to those children who do not use an insecticide-treated net (ITN), but who received the DTP3 vaccine, was also estimated. Results Uptake of DTP3 was higher than malaria intervention coverage in most countries. Overall, 34% of children did not use ITNs and received DTP3, while 35% of children used ITNs and received DTP3, although this breakdown varied by country. It was estimated that there are 33 million children in these 20 countries who do not use an ITN. Of these, 23 million (70%) received the DTP3 vaccine. Vaccinating those 23 million children who receive DTP3 but do not use an ITN could avert up to an estimated 9.7 million (range 8.5–10.8 million) clinical malaria cases each year, assuming all children who receive DTP3 are administered all four RTS,S doses. An additional 10.8 million (9.5–12.0 million) cases could be averted by vaccinating those 24 million children who receive the DTP3 vaccine and use an ITN. Children who had access to or used an ITN were 9–13% more likely to reside in rural areas compared to those who had neither intervention regardless of vaccination status. Mothers’ education status was a strong predictor of intervention uptake and was positively associated with use of ITNs and vaccination uptake and negatively associated with having access to an ITN but not using it. Wealth was also a strong predictor of intervention coverage. Conclusions Childhood vaccination to prevent malaria has the potential to reduce inequity in access to existing malaria interventions and could substantially reduce the childhood malaria burden in sub-Saharan Africa, even in regions with lower existing DTP3 coverage.

The assembly effect: the connectedness between populations is a double‐edged sword for public health interventions

Background Many public health interventions lead to disruption or decrease of transmission, providing a beneficial effect for people in the population regardless of whether or not they individually participate in the intervention. This protective benefit has been referred to as a herd or community effect and is dependent on sufficient population participation. In practice, public health interventions are implemented at different spatial scales (i.e., at the village, district, or provincial level). Populations, however defined (i.e., neighbourhoods, villages, districts) are frequently connected to other populations through human movement or travel, and this connectedness can influence potential herd effects. Methods The impact of a public health intervention (mass drug administration for malaria) was modelled, for different levels of connectedness between populations that have similar disease epidemiology (e.g., two nearby villages which have similar baseline malaria incidences and similar malaria intervention measures), or between populations of varying disease epidemiology (e.g., two nearby villages which have different baseline malaria incidences and/or malaria intervention measures). Results The overall impact of the interventions deployed could be influenced either positively (adding value to the intervention) or negatively (reducing the impact of the intervention) by how much the intervention units are connected with each other (e.g., how frequent people go to the other village or town) and how different the disease intensity between them are. This phenomenon is termed the “assembly effect”, and it is a meta-population version of the more commonly understood “herd effect”. Conclusions The connectedness of intervention units or populations is an important factor to be considered to achieve success in public health interventions that could provide herd effects. Appreciating the assembly effect can improve the cost-effective strategies for global disease elimination projects.

Factors Associated with Malaria Infection among Head Porters in Agbogbloshie Market in the Greater Accra Region of Ghana

Background. Head porters constitute the mobile population who are at an increasing risk of being infected with malaria. They move around the city to carry out their duties with no accommodation. Therefore, they sleep wherever they find themselves in the evening and do not benefit from most of the malaria intervention programs such as the use of long-lasting insecticide net. The inability to identify them because they are mobile means that they can continue to drive malaria transmission even if malaria in the general population is controlled. Objectives. This study assessed the factors associated with malaria infection among head porters in the Agbogbloshie market in the Greater Accra Region of Ghana. Method. A total of 218 head porters were recruited from the Agbogbloshie market, and blood samples were collected from participants to test for malaria parasite infection using Rapid Diagnostic Test (RDT) and microscopy and were interviewed using a closed-ended questionnaire. The data were analyzed using Stata version 15. Simple descriptive statistics, Pearson chi-square, and Multiple Logistic Regression were performed with significance set at <0.05. Result. The study revealed 12% ( CI 95 % = 8.2 ‐ 16.9 ) and 9.6% ( CI 95 % = 6.3 ‐ 14.4 ) infection of malaria using RDT and microscopy, respectively. Plasmodium falciparum (21/218) was the main parasite detected in all positive blood samples. Age and marital status are significant factors associated with malaria infection among head porters. Age group 40 years and above had 89% ( AOR 0.11 CI 95 % = 0.01 ‐ 0.98 ) reduced odds of getting malaria compared to those below 20 years, while those who are single are 3.52 times more likely to be infected with malaria compared with those who are married ( AOR 95 % CI = 3.52 1.13 ‐ 10.92 ). Conclusion. This study concludes that the increasing age of head porters significantly decreased the probability of malaria infection, while head porters who are single have greater odds of being infected with malaria. Age and marital status are important factors to be considered for malaria intervention programs in head porters.

Analysis of the potential for a malaria vaccine to reduce gaps in malaria intervention coverage

BackgroundThe RTS,S/AS01 malaria vaccine is currently being piloted in three African countries. We sought to identify whether vaccination could reach additional children who are at risk from malaria but do not currently have access to, or use, core malaria interventions.MethodsUsing data from household surveys we calculated the overlap between malaria intervention coverage and childhood vaccination (diphtheria-tetanus-pertussis dose 3, DTP3) uptake in 20 African countries with at least one first administrative level unit with Plasmodium falciparum parasite prevalence greater than 10%. We used multilevel logistic regression to explore patterns of overlap by demographic and socioeconomic variables. We also estimated the public health impact of delivering RTS,S/AS01 to those children who do not use an insecticide-treated net (ITN) but who received the DTP3 vaccine.ResultsUptake of DTP3 was higher than malaria intervention coverage in most countries. Overall, 34% of children did not use ITNs and received DTP3, while 35% of children used ITNs and received DTP3, although this breakdown varied by country. We estimated that there are 33 million children in these 20 countries who do not use an ITN. Of these, 23 million (70%) received the DTP3 vaccine. Vaccinating those 23 million children who receive DTP3 but do not use an ITN could avert an estimated 9.7 million clinical malaria cases each year. An additional 10.8 million cases could be averted by vaccinating those 24 million children who receive the vaccine and use an ITN. Children who had access to or used an ITN were 9 to 13% more likely to reside in rural areas compared to those who had neither intervention regardless of vaccination status. Mothers’ education status was a strong predictor of intervention uptake and was positively associated with use of ITNs and vaccination uptake and negatively associated with having access to an ITN but not using it. Wealth was also a strong predictor of intervention coverage.ConclusionsChildhood vaccination to prevent malaria has the potential to reduce inequity in access to existing malaria interventions and could substantially reduce the childhood malaria burden in sub-Saharan Africa, even in regions with lower existing DTP3 coverage.