More on vaccine efficacy trial.
D000818:Animals; D001428:Bacterial Vaccines; D002417:Cattle; D002418:Cattle Diseases / Q000517:prevention & control*; D010325:Pasteurella / Q000276:immunology*; D010326:Pasteurella Infections / Q000517:prevention & control / Q000662:veterinary*
D001428:Bacterial Vaccines