Sentence: The high incidence of imported malaria ( 0.70 % ) and the low costs of providing chemoprophylaxis resulted in a cost-benefit ratio of 0.19 for chloroquine and proguanil and 0.57 for a regimen containing mefloquine .
Drug combination annotation:
[{'class': 'POS', 'spans': ['chloroquine', 'proguanil'], 'is_context_needed': False}]