The outbreak, first confirmed Nov. 29, has spread through three provinces and forced authorities to destroy more than 224,000 animals, the Yonhap News Agency reported Wednesday.
The extent of the vaccinations has not been decided as various factors need to be checked and considered, authorities said.
"A decision may be made at the expert meeting of the livestock quarantine consultation committee chaired by the farm minister," an official at the Ministry for Food, Agriculture, Forestry and Fisheries said.
The ministry said 44 cases of foot-and-mouth disease have been confirmed so far in North Gyeongsang, Gyeonggi and Gangwon provinces.
Vaccinating 100,000 head of cattle or pigs could cost $520,000 or even more as the number of vaccination shots required could go up, officials said.
Authorities estimated the cost of the destroyed animals had already exceeded $200 million.