But natural selection is a powerful force, and if the spread of the disease means they have to be used widely, a resistant strain of the virus could easily evolve.

• 但是自然选择是一股强大的力量，如果说疾病的传播意味着这种药物被广泛地应用，那么一种新的抗药性病毒株很可能迅速出现。