Vaccine induced serum antibody levels were significantly less in pigs with passive immunity to Mycoplasma hyopneumoniae compared to pigs without passive immunity. Age at vaccination did not influence antibody responses to vaccination. The presence of passive antibodies at the time of vaccination may provide an explanation for vaccination failure under field conditions.
Iowa State University
Thacker, Brad J.; Boettcher, Tamara B.; Anderson, Tammy S.; Thacker, Eileen L.; and Young, Theresa F., "The Influence of Passive Immunity on Serological Responses to Mycoplasma hyopneumoniae Vaccination" (1998). Swine Research Report, 1997. 45.