There were significant differences in seroprevalence to P. falciparum antigens between rounds, with the highest seroprevalence seen in round 3 for both sites. Seroprevalence was consistently higher in Butemba than in Aduku, indicating a higher level of malaria exposure. Age was highly associated with seropositivity for all antigens. There was a slight increase in seroprevalence to P. falciparum antigens between round 1 and round 3 for all age groups in both sites in Uganda, but a particularly significant increase in the under-five age group in Aduku. This may suggest a recent increase in transmission. For both sites, the seroconversion rate (SCR) increased by 45% and 32% respectively between rounds 1 and 3, and then decreased by 47% and 40% between rounds 3 and 4. This indicates increased transmission intensity in round 3 compared to rounds 1 and 4.
In the Ethiopian sites, there was a substantial reduction in seroprevalence to P. falciparum and P. vivax over time. Seroprevalence in Hembecho was higher than in Guba. In Hembecho, there was a significant decrease in seroprevalence to both P. falciparum and P. vivax in all age groups except for people over age 45 in rounds 3 and 4 compared to round 1. This indicates decreased exposure after round 1. In Guba, the decrease in seroprevalence to both species was not significant in all but the 15-44 age group. In Hembecho and Guba, 75% and 66% reduction was observed in SCR between rounds 1 and 3, respectively, suggesting a substantial reduction in transmission intensity for both parasite species after round 1.