modified smallpox

例句：

1. 1. The vaccine against smallpox has been modified to be more effective.
   针对天花的疫苗已经被改良，效果更佳。
2. 2.The researchers have made significant progress in modifying the virus.
   研究人员在修改病毒方面取得了显著进展。
3. 3. The smallpox vaccine is a crucial tool for preventing the disease.
   天花疫苗是预防该疾病的关键工具。