Effect of malaria chemoprevention for school-age children across transmission archetypes: a modelling study

Background
Intermittent preventive treatment (IPT) of school-aged children with antimalarial drugs decreases rates of infection, anaemia, and clinical malaria. Since school-aged children are a major transmission reservoir, we estimated the effect of IPT for this group on Plasmodium falciparum transmission to younger children and adults across three epidemiological settings.

Methods
With the use of an established malaria transmission model, we developed three epidemiological archetypes (Sahelian, Central, and Southern African) and estimated the effect of IPT of school-age children across transmission levels (P falciparum parasite rate in children aged 2–10 years [PfPR2–10]: 5–40%). Long-lasting insecticide-treated nets and clinical case management were always included as baseline interventions. We compared scenarios for three of the most widely studied drug options (dihydroartemisinin–piperaquine, artesunate–amodiaquine, and sulfadoxine–pyrimethamine–amodiaquine) and delivery options (school-based or community-based), estimating clinical cases averted.

Findings
When long-acting drugs were administered frequently (monthly campaigns with dihydroartemisinin–piperaquine), modelled IPT of school-age children averted 70–90% of cases in school-aged children (up to about 2·0 cases per child per year) and 20–60% of cases in younger children and adults (up to about 0·5 cases per person per year), with greater community benefit at lower transmission levels (PfPR2–10 5–10%). Shorter-acting drugs (sulfadoxine–pyrimethamine–amodiaquine in the Sahelian archetype or artesunate–amodiaquine in the Central and Southern archetypes) administered monthly or longer-acting drugs administered once per school term averted 40–60% of cases in school-aged children (up to about 1·3 cases per child per year) and 15–50% of cases in other ages (up to about 0·5 cases per person per year).

Interpretation
Our model suggests that adding IPT of school-age children to current control tools could decrease malaria burden in this group and reduce P falciparum transmission.