Swine vaccination reduces incidence but is not 100% effective.

• A. True
• B. False
• C. Not sure
• D. Not applicable

Answer: (A)

Vaccination lowers the chance that swine will get disease and often reduces how severely they are affected, but no vaccine provides perfect protection in every animal. In swine, vaccines are used to reduce incidence and often lessen disease severity and shedding, which helps control outbreaks at the herd level. However, several real‑world factors prevent 100% effectiveness: differences between vaccine strains and circulating pathogens, interference from maternal antibodies in young pigs, timing and number of doses, stress or poor nutrition, improper administration, and varying individual immune responses. Because of these factors, some vaccinated animals may still become infected or shed organisms, though typically at a lower rate or with milder illness. This is why the statement that vaccination reduces incidence but is not 100% effective is true.