Is there cross protection among the seven FMD serotypes?

• A. There is complete cross protection among all seven serotypes.
• B. There is no cross protection among the seven serotypes.
• C. Cross protection exists only among some serotypes.
• D. Cross protection is guaranteed by current vaccines.

Answer: (B)

The key idea is that protection against FMDV is serotype-specific. The seven serotypes (O, A, C, SAT1-3, Asia1) have distinct surface antigens, so antibodies generated against one serotype generally do not neutralize or protect against another. Because of this, there is no meaningful cross-protection among different serotypes; infection or vaccination with one serotype does not reliably shield you from others. That's why FMD vaccines are formulated as multivalent products that include the relevant serotypes for a region, and why protection cannot be guaranteed across all seven serotypes with a single serotype vaccine. Some limited cross-reactivity can occur within the same serotype or among very closely related strains, but it’s not dependable cross-protection across different serotypes.