According to the LPBELISA kit procedure, yaks with antibody titers ≥ 1:128 were considered to have acquired 99% protection against FMDV. Analogously, yaks with antibody titers between 1:16 and 1:128 were considered to have acquired 50% protection. Yaks with antibody titers ≤ 1:16 were considered to have acquired no protection.