Vaccines: What is their role?

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Vaccines can provide a good start which is essential for healthy pigs.

It is essential that producers get the most value from the vaccines they choose to use. OLIVER DURAN* considers some important factors to consider when selecting your vaccine.

Vaccines are the cornerstone of disease prevention on swine farms in Asia and globally. Prevention of disease is critical to sustainable and predictable pork production, which leads to profitability and long-term success. Before discussing vaccines, we should understand the major trends affecting the swine industry. According to John Pluske, Honorary Professorial Fellow at The University of Melbourne, there are several mega trends that will continue to impact and challenge pork production and profitability into the future. These are:

• Food safety – how our food is produced and processed

• Welfare and treatment of animals will always be paramount

• Environmental sustainability and stewardship

• Reduced antibiotic use and enhanced antimicrobial stewardship

He stated in a virtual event: “This is the age of consumer empowerment. Consumers will continue to push for greater trust and transparency in farming and farmers, veterinarians and processors, and in the entire food supply chain.”

The bottom line is clear – expectations from consumers will be higher; consumers will increasingly want to feel good about their pork. Therefore, we believe that for the sustainable future of the industry we will need to focus on the 4 P’s: People, Pigs, the Planet and Profit.

For this reason, vaccination programs should address these needs – programs that are easy and safe for farm workers, safe and efficacious for pigs, that prevent losses from disease increase profitability, and finally resulting in benefits to the environment by reducing inefficiency and impact on natural resources.

Table 1: What do these scientific facts mean to you in practice? Using the example of a baculovirus expressed vaccine.

What should you consider when choosing vaccines?

Pig farmers worldwide rely more and more on prevention of infectious disease to safeguard profitability of their production. Beside biosecurity (external and internal), vaccination is the most important measurement for disease prevention in swine production. Pig producers and vets rank vaccine efficacy as the utmost important criteria for choosing vaccines. In a worldwide survey, 93 %
of the farmers ranked efficacy of a vaccine as the most important for their decision making. Efficacy was followed by safety and by convenience as the third reason mentioned.

Efficacy

Modern vaccines need to demonstrate efficacy at the lowest titer allowed on their label, both to show early protection (so called onset of immunity) and for the duration specified on the label (duration of immunity). Production quality is ensured by having a strict outline of production with consistent processes, ingredients, and quality control.

To better understand a vaccine, we should look at how vaccines work and interact with the immune system. One important goal of immunology research is to establish indicators of efficacy for certain pathogens and vaccines. The outcome of this research can help how to use current vaccines best but also with the development of future vaccine technology.

Figure 1: Predominant PCV2 genotypes detected in Asia.

Effectiveness in the presence of maternal immunity

Another important aspect is the need to create an immune response in the presence of maternally derived antibodies (MDA), as typically in the field we vaccinate piglets that come from sows that already have immunity. Not all vaccines can work in those conditions and therefore vaccination needs to be delayed until the MDA has sufficiently declined. But some can. For example, when controlling PCV2 Disease, most pigs are antibody positive in early life. In a study analyzing over 6000 pigs from farms with subclinical disease, it was demonstrated that the vaccine used in the study (Ingelvac CircoFlex) was effective when applied around 3 weeks of age and was not affected by the level of MDA at the time of vaccination. The PCV2 vaccination controlled the clinical disease as well as improved production parameters. Results showed that the use of the vaccine was able to decrease the PCV2 viremia and increase average daily weight gain (ADWG) in vaccinated piglets compared to non-vaccinated ones. The overall difference of ADWG between both groups was close to 30 g/day
(p <0.05), also when they were split for low and high levels of MDA titers. The vaccinated animals grew faster compared to unvaccinated control animals, regardless of the level of maternal antibodies present at the time of vaccination.

Table 2: Summary of published studies demonstrating cross protection of a PCV2-a based vaccine (Ingelvac CircoFlex) against the most prevalent genotypes of PCV2.

Effectiveness against the strains circulating on your farm

PCV2 and PRRSV are two of the main viral pathogens threatening the swine industry. Both have a high degree of genetic change due to mutation, recombination and constant evolution in Asia and worldwide. Therefore, it is vital to show that protection from vaccines continues to be effective by testing them against the most recent strains circulating in farms. For PRRS vaccination, laboratory and farm trials have shown that Ingelvac PRRS MLV has continued to show efficacy despite a huge rate of genetic change (see Interactive X-protection tool. The power to X-protect | PRRS.com). 

While its rate of genetic change is not as extensive, PCV2 virus has been shown to have various genotypes, with three of them (PCV2a, PCV2b and PCV2d) known to be the most common.

Again, it is critical that we continue to monitor the efficacy of the existing vaccines. Data from field studies carried out in Asia and other continents (Table 2) show that Ingelvac CircoFlex continues to provide solid cross-protection against emerging genotypes as demonstrated by billions of healthy vaccinated pigs.

Conclusion

It is important that pork producers in Asia carefully select their vaccines to ensure that they can benefit the health of their pigs and ensure that the 4P’s are taken care of, Pigs, People, Profit, and the Planet. The right vaccine choice will deliver healthy pigs, satisfied workers, solid profitability, and efficient production to optimize the use of feed.

*Oliver Duran ([email protected]) is Global Strategic Marketing Swine with Boehringer-Ingelheim Animal Health. References are available on request to the author. If you would like to learn more please visit the website www.PRRS.com (PCV2 Cross Protection Know the Facts.pdf (prrs.com)). For more information on cross-protection and PRRS in Asia you can view more details (Type 1 and type 2 PRRSV and Cross Protection: What does the science say? | PRRS.com).

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Based and working in the region.