Evaluation of the efficacy and duration of immunity of a bivalent subunit vaccine containing porcine circovirus type 2a and type 2d antigen.

Porcine circovirus type 2 (PCV2) vaccination has been effective in protecting pigs from clinical disease and is used extensively today. Studies in vaccinated populations across the world indicate a major PCV2 genotype shift towards genotype 2d (PCV2d) becoming the predominant genotype, with genotype PCV2a still being a prevalent genotype. Here we present a series of studies that evaluated a novel commercial subunit vaccine, including both PCV2a and PCV2d antigens, Ingelvac CircoFLEX® AD, to protect pigs against PCV2 associated disease and provide homologous protection against PCV2a or PCV2d. Cesarean-derived, colostrum-deprived pigs were blocked by litter and randomly assigned to Placebo Control and Vaccine groups which received the novel vaccine. Six studies were carried out to determine efficacy at two weeks of age, the onset of immunity, and the duration of immunity after challenge with PCV2a or PCV2d. Across all six studies, 55 to 100% of Control pigs were positive for depletion and colonization while only 4 to 44% of Vaccine pigs were positive for depletion and colonization with statistically significant differences for each study, P ≤ 0.0031. These results support the efficacy of the novel vaccine against challenge by both PCV2a and PCV2d at 2 weeks of age, an onset of immunity of 2 weeks after vaccination, and 26 weeks duration of immunity.