Systematic Veterinary Virology

VACCINATION

• The use of killed or modified-live vaccines can provide protection by decreasing the consequences of acute infections.
• However, it is questionable whether killed or modified-live vaccines provide complete foetal protection from the development of in utero fetal infections.
• In a breeding herd all breeding females 3-6 weeks prior to breeding should be vaccinated. Both modified-live (MLV) and killed vaccines are available commercially, generally as a component in multivalent vaccines.
• Modified live virus (MLV) vaccines can potentially infect the fetus so should not be given to pregnant cows. The inactivated vaccines are safe but must be given twice, two to four weeks apart.