MLV vaccines must replicate after inoculation to produce enough antigen to produce an immune response. Killed virus vaccines contain viruses that have been treated by chemical or physical means to prevent them from replicating in the vaccinate. Additional disadvantages that have been associated with MLV BVD vaccines in particular include immunosuppression and induced disease in some immunologically tolerant animals. Vaccination is an important part of any preventative medicine program, but decisions regarding specific vaccination recommendations are often difficult on geographic area, herd size, health history, existing disease conditions, risk of exposure, individual management practices, etc. A wide diversity of opinions exists on the best vaccination protocol.
Greater controversy exists over vaccination procedures under outbreak conditions.
Designing and recommending immunizing programs can be a challenge that requires a considerable amount of professional judgment. Veterinarians have a professional obligation to educate themselves and their clients on the currently accepted vaccination practices. Animalvowners are encouraged to consult their veterinarian when designing preventative animal health programs. While there is considerable evidence that currently available vaccines are protective against challenge with Type 1 viruses, it is unknown whether curently available vaccines are equally protective against the Type 2 viruses. Current epidemiological evidence suggests that current vaccines are partially protective.