Recovered animals produce antibody and resist reinfection by the same subtype of virus for up to one year or more. When immunity has waned, re-exposure to the original subtype can result in a local infection which results in virus excretion without clinical symptoms.

If re-exposure is to a second serotype or subtype there is little or no resistance to clinical disease. This is one reason why vaccination is not used in the UK. If the UK vaccinated it would be classed as an FMDV-enzootic area with a loss of certain meat export markets until all vaccinated stock had been culled.