Adverse events in the first 12 weeks of treatment led to discontinuation of simeprevir in two ( < 1 % ) patients and discontinuation of placebo in one patient ( < 1 % ) ; fatigue ( 106 [ 40 % ] vs 49 [ 38 % ] patients , respectively ) and headache ( 81 [ 31 % ] vs 48 [ 37 % ] , respectively ) were the most common adverse events .