疫苗在上個世紀直到今日，一直是有效對抗傳染疾病的主角，疫苗的使用成本便

疫苗在上個世紀直到今日，一直是有效對抗傳染疾病的主角，疫苗的使用成本便宜，一直是它能普遍應用而產生卓越效果的主要原因。

結果 (英文) 1:

Vaccine in the last century until today, has been the protagonist effective against infectious diseases, vaccine cost is cheap, it has been widely used to produce mainly due to excellent effect.

結果 (英文) 2:

Vaccines have been the main players in the fight against infectious diseases throughout the last century, and the low cost of using vaccines has been the main reason for its universal use and its remarkable results.

結果 (英文) 3:

Vaccine has been the main role in fighting against infectious diseases since last century. The low cost of vaccine is the main reason why it can be widely used and produce excellent results.