title: Letter: S19 and 45-20 vaccine.
mesh_terms: D000818:Animals; D001428:Bacterial Vaccines / Q000009:adverse effects*; D002007:Brucellosis, Bovine / Q000517:prevention & control*; D002417:Cattle; D002418:Cattle Diseases / Q000517:prevention & control; D003168:Complement Fixation Tests; D007117:Immunization, Secondary
chemical_list: D001428:Bacterial Vaccines