Efficacy and Safety Evaluation of a Ready-to-Use Bivalent Porcine Circovirus Type 2 and Mycoplasma hyopneumoniae Vaccine in China

<b>Background/Objectives:</b> Porcine Circovirus Type 2 (PCV2) and <i>Mycoplasma hyopneumoniae</i> are primary pathogens causing respiratory disease in pigs. Recently, a Ready-to-Use bivalent PCV2 and <i>M. hyopneumoniae</i> vaccine has been registered in China. The aim of this randomized, side-by-side trial was to evaluate the efficacy and safety of this vaccine under field conditions in a Chinese commercial pig farm. <b>Methods:</b> In total, 938 piglets were allocated to three groups-A (tested vaccine), B, C-and vaccinated according to different schemes. Efficacy was assessed by Average Daily Gain (ADG), pneumonia lesions at slaughter and PCV2 viremia. Systemic reactions were recorded after vaccination to evaluate safety. <b>Results:</b> ADG was higher in group A compared with other vaccination schemes. The prevalence of pneumonia lesions was significantly lower in group A. PCV2 viremia was overall low in all groups, with no reported differences. No severe or moderate systemic reactions were observed after vaccination. Only four pigs showed mild reactions (A: 2/320, B: 2/309; C: 0/309). <b>Conclusions:</b> Under these conditions, the tested vaccine was proved to be efficacious in increasing ADG and reducing pneumonia at slaughter by protecting against both PCV2 and <i>M. hyopneumoniae</i> field infections. It can also be concluded that the Ready-To-Use bivalent vaccine was safe.