Field efficacy comparisons of Suvaxyn PCV2 and other commercial PCV vaccines

Porcine circovirus-associated disease (PCVAD) is a challenging and costly health issue for the U.S. swine industry. Infection can cause significant reduction in pig performance and growth rate, and increased mortality, resulting in severe economic losses in swine herds. Porcine circovirus type 2 (PCV2) vaccines play a significant role in reducing mortality rates and improving growth performance.

In 2006, Fort Dodge Animal Health (FDAH) introduced Suvaxyn PCV2 to aid in the prevention of viremia and aid in the control of lymphoid depletion caused by porcine circovirus type 2. Suvaxyn PCV2 is the only PCV2 vaccine with a flexible dosing option that can be delivered with either a single 2 mL dose to pigs 3 weeks of age or older — providing at least a four-month duration of immunity (DOI) — or a 1 mL dose at 3 weeks of age followed by a second 1 mL dose three weeks later. In two field trials, Suvaxyn PCV2 was compared to two other commercially available vaccines.¹

Two Midwestern trials were conducted to test the efficacy differences between three commercially available vaccines. The first trial (Trial A) was conducted using real-world conditions in a wean-to-finish barn; the second trial (Trial B) was conducted at a research nursery-to-finish facility.

In Trial A, 1,200 pigs were divided into six treatment groups with 200 pigs in each group. All pigs were between 18 and 22 days old. Pigs (vaccinates and controls) were then commingled in each pen. The six treatment groups consisted of:

• Suvaxyn PCV2 given as a 2 mL dose at 3 weeks of age.
• Suvaxyn PCV2 given as a 2 mL dose at 5 weeks of age.
• Suvaxyn PCV2 given as a 1 mL dose at 3 and 5 weeks of age.
• Intervet Circumvent^® PCV given as a 2 mL dose at 3 and 5 weeks of age.
• Boehringer Ingelheim Ingelvac CircoFLEX^® given as a 1 mL dose at 3 weeks of age.
• Sterile water for the control group given as a 2 mL dose at 3 and 5 weeks of age.

Serum samples were collected from 50 pigs (25 percent) at weaning (Day 0), and then two, five, eight, 12, 16 and 20 weeks post vaccination (WPV). Polymerase chain reaction (PCR) testing monitored viremia levels. All pigs were weighed at weaning (Day 0) and again just prior to market (Day 141).

In Trial B, 1,000 pigs from 18 to 22 days old were housed at a research nursery site. Pigs were allotted to one of 48 pens, with 23 pigs per pen. The pigs were housed separately by each treatment group (250 pigs per group). The four treatments included:

• Suvaxyn PCV2 given as a 2 mL dose at 3 weeks of age.
• Intervet Circumvent^® PCV given as a 2 mL dose at 3 and 5 weeks of age.
• Boehringer Ingelheim Ingelvac CircoFLEX^® given as a 1 mL dose at 3 weeks of age.
• Sterile water given as a 2 mL dose at 3 weeks of age.

In Trial A, all Fort Dodge Suvaxyn PCV2-vaccinated groups and the Circumvent PCV treatment group showed strong post-vaccination seroconversion. In contrast, the Ingelvac CircoFLEX group did not seroconvert to PCV2 until field PCV2 exposure, which occurred around five weeks post vaccination. The percentage of PCV2-positive pigs, as detected by PCR for PCV2 viremia, was significantly reduced in the three Fort Dodge Suvaxyn PCV2 treatment groups and the Circumvent PCV treatment group (see Figure 1).

Mortality rates were low in all five vaccinated groups, but exceeded 8.5 percent for the control group (see Figure 2).

Blood and tissue samples collected during the trial showed the pigs were negative for Porcine Reproductive and Respiratory Syndrome (PRRS), but tested positive for Swine Influenza Virus (SIV). The percentage of pigs marketed in all vaccinated treatments (94.3–97.4 percent) was significantly improved compared with controls (88.1 percent). The total number of pounds marketed was significantly increased in all vaccinated treatment groups compared with the control group (see Figure 3).

In Trial B, the Fort Dodge and Intervet treatment groups showed the same pattern of seroconversion as Trial A, while the Boehringer Ingelheim and control groups did not seroconvert until field PCV2 exposure, which occurred around eight weeks post vaccination. Pig mortality was not significantly different among the PCV2-vaccinated groups; however, mortality was higher in the unvaccinated treatment group (see Figure 4).

The percentage of PCV-positive pigs was significantly reduced in the Fort Dodge Animal Health and Intervet groups (see Figure 5).

Pigs vaccinated with Suvaxyn PCV2 showed significant protection against the detrimental effects of PCV2 and improved growth performance compared with unvaccinated pigs. While the Intervet and Boehringer Ingelheim PCV2 vaccines also provided reduced mortality, Suvaxyn PCV2 outperformed Ingelvac CircoFLEX in prevention of PCV2 viremia. PCV2 viremia may not always cause a negative impact on pig performance, but co-infection of PCV2 with other swine pathogens (PRRS, Mycoplasma, SIV) or physical defects (swollen joints, lameness, hernia) could trigger the onset of PCVAD. In addition, pigs with PCV2 viremia will likely increase the difficulty of controlling and eradicating PCVAD due to PCV2 shedding and its subsequent spreading to barns, transport trucks and harvest sites.