It belongs to a group of viruses that includes the smallpox virus ( variola), the virus used in the smallpox vaccine ( vaccinia), and the cowpox virus. 它属于一个包括天花病毒、在天花疫苗中采用的病毒和牛痘病毒的病毒组。
Variola virus belongs to the genus of orthopoxvirus, and there are some other infectious members, such as Vaccinia virus, cowpox virus, and monkeypox virus. 在正痘病毒属还有另外几种病毒对人具有一定的感染性,如痘苗病毒、牛痘病毒和猴痘病毒。