Comparative Safety and Efficacy of Commercial Porcine Vaccines Against Mycoplasma hyopneumoniae and Porcine Circovirus Type 2 (PCV2)

Mycoplasma hyopneumoniae (Mhyo) and porcine circovirus type 2 (PCV2) infections cause enormous economic losses in the swine production sector. Vaccination remains the most effective strategy against the complex clinical entities caused by these pathogens. While effective vaccines against PCV2 are available, immunisation against Mhyo continues to be challenging. In parallel, intradermal (ID) vaccination can optimise time and costs while providing faster and user-safe administration. This study compares the safety and efficacy of commercial porcine vaccines against Mhyo and PCV2, including intramuscular (IM) and ID ones: (1) ID recombinant Mhyo-PCV2, (2) ID recombinant PCV2 + ID inactivated Mhyo, (3) IM bivalent inactivated Mhyo and recombinant PCV2, (4) IM bivalent inactivated Mhyo and inactivated chimeric PCV1-PCV2 and (5) IM inactivated Mhyo + IM inactivated PCV2. Safety, evaluated through clinical signs, adverse effects, local reactions, and average daily weight gain, has been confirmed for all vaccines. Following challenge with both pathogens, all products reduced PCV2 viremia and faecal shedding, proving efficacy against PCV2 infection. In contrast, only the ID recombinant Mhyo-PCV2 and the IM inactivated Mhyo + IM inactivated PCV2 vaccines, significantly reduced lung lesions related to Mhyo infection, indicating a better protection compared to the other vaccines.