NBME Form 11 Practice Test

Vaccinia virus is used in the smallpox vaccine because it’s a related poxvirus that triggers immune responses cross-protective against variola, the smallpox virus. As a live vaccine, vaccinia replicates in the skin and generates both antibody and T-cell responses that recognize shared antigens with variola, providing immunity to smallpox. The other diseases listed are prevented by vaccines targeting their specific pathogens (measles by a measles virus vaccine, influenza by influenza vaccines, polio by poliovirus vaccines), not by vaccinia.