Randomisation and masking
Eligible participants were randomly assigned 1:1 to one of the two treatment groups according to a computer-generated randomisation schedule. Randomisation was in permuted blocks of size ten and stratified by village. Individual, sealed, and sequentially numbered opaque envelopes were provided for each trial site, with one envelope per participant indicating the treatment allocation. Allocation was done by trained study staff drawing the next envelope, which contained the study number and treatment allocation. An open-label design was selected due to unavailability of a suitable placebo that was identical in appearance to artemether–lumefantrine. Masking of investigators or participants was not possible. The randomisation procedure allowed for drug allocation concealment before envelopes were opened. All laboratory investigations were performed without knowledge of the treatment allocation.