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

## TL;DR

This study compares different pig vaccines against two common respiratory diseases, finding that some vaccines better reduce lung damage and support animal health.

## Contribution

The study identifies specific vaccination strategies that offer superior protection against Mycoplasma hyopneumoniae while being safe and effective.

## Key findings

- All vaccines were safe and did not affect pigs' growth or cause adverse effects.
- Only the intradermal recombinant Mhyo-PCV2 and intramuscular inactivated Mhyo + PCV2 vaccines significantly reduced lung lesions from Mycoplasma.
- All vaccines effectively controlled PCV2 viremia and fecal shedding.

## Abstract

Respiratory diseases caused by Mycoplasma hyopneumoniae (Mhyo) and porcine circovirus type 2 (PCV2) are common in pig farms and can seriously affect animal health, wellbeing, and productivity. Vaccination is essential to prevent these problems, but available vaccines differ in both administration route and efficacy. In this study, several commercial vaccines were compared under controlled conditions, including products administered either intramuscularly or intradermally using a needle-free device. All vaccines proved to be safe and did not negatively affect the animals’ growth. When pigs were exposed to both infectious agents, all vaccines controlled the virus responsible for circovirus disease. However, only the intradermal recombinant Mhyo-PCV2 vaccine and the intramuscular inactivated Mhyo + intramuscular inactivated PCV2 vaccine markedly reduced the lung damage associated with Mycoplasma infection. These results can provide practical information for farmers and veterinarians, showing how certain vaccination strategies may offer better disease protection while also supporting animal welfare and efficient farm management.

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.