Response of sheep vaccinated with large doses of vaccine to challenge by airborne foot and mouth disease virus.

Administration of three-fold or six-fold larger doses of conventional monovalent type O foot and mouth disease (FMD) vaccine to sheep prevented viraemic distribution of virus after exposure to airborne virus one week later. However, virus replication in the respiratory tract or excretion in oesophageal-pharyngeal fluids and breath was not prevented. The implication of these findings for the use of vaccine as an adjunct to a 'stamping out' policy for countries which are free from FMD and which do not practice mass annual vaccination are discussed.