June 9, 2022

 

Zoetis' bivalent vaccine outperformed monovalent vaccine amid emerging PCV2 variants

 


Zoetis Inc. announced on June 8 that new research recently published in the peer-reviewed journal Veterinary Research and shared at the American Association of Swine Veterinarians 2022 Annual Meeting shows that when compared to monovalent vaccines against the fast-evolving porcine circovirus type 2 (PCV2), the company's Fostera Gold PCV MH bivalent vaccine demonstrated reduced viremia and fecal shedding in a challenge study.

 

"The new study suggested that the virus protection was better when using the bivalent vaccine compared to a monovalent, even when the monovalent was the same as the challenge," said Dr. Meggan Bandrick, director of Global Biologics Research for Zoetis. "That's important because we know that PCV2 is evolving and exists on a continuum, based on the epidemiological patterns we see in the field. So having both PCV2a and PCV2b in the vaccine offered protection against the continuum, in a study."

 

The research demonstrated that:

 

    - A bivalent PCV2 vaccine (PCV2a/b) should offer improved coverage due to homologous protection against the variable PCV2 strains circulating in swine herds;

 

    - A bivalent PCV2 vaccine showed a decrease in viremia and fecal shedding compared to monovalent vaccines;

 

Identified in 2012, PCV2d is the predominant genotype circulating in the United States, accounting for a majority of PCV2 infections.

 

"While the predominant strain globally is PCV2d, pigs are still exposed to PCV2a and PCV2b," Dr. Bandrick said. "The PCV2b and PCV2d viruses are genetically similar, and we do know there's cross-protection."

 

A recent comparative evaluation of growth performance in 21-day old pigs suggested that pigs vaccinated with vaccines containing PCV2a, PCV2b and Mycoplasma hyopneumoniae (Mhp) exhibited significantly better growth performance when compared with pigs vaccinated with vaccines containing only PCV2a and Mhp, potentially due to increased coverage against the field PCV2d strain. The PCV2a/b and Mhp vaccinated pigs also reduced the amount of PCV2d loads in the blood and feces and resulted in a lower Mhp load in the larynx when compared with PCV2a and Mhp vaccinated pigs.

 

First introduced in 2018, Fostera Gold PCV MH is the only vaccine to contain two PCV2 genotypes — 2a and 2b — and Mhp coverage. Together, the two genotypes provide the broadest antigenic coverage4-8 against evolving PCV2 viruses in US swine herds as well as the longest-lasting, with a 23-week duration of immunity.9-13

 

"All of these strains are circulating, but most of the vaccines are based exclusively on PCV2a. But when we have PCV2a and PCV2b in the vaccine, the benefit is that pigs develop a broader immune response so that they can be protected when encountering different strains in the field."

 

Fostera Gold PCV MH has been predicted to have on average 34% more antigenic coverage than competitor vaccines to PCV2 strains, and now Fostera Gold PCV MH and Fostera Gold PCV are the only PCV2 vaccines approved as safe for use in pregnant sows and gilts.

 

A recent field study with a total of 359 pregnant sows and gilts across all gestational stages received either Fostera Gold PCV MH or saline, administered once intramuscularly.

 

Safety was assessed by the following variables: sow adverse health events, injection site evaluations, reproductive outcomes and litter health observations. There were zero injection site reactions post-vaccination. Reproductive outcomes and litter performance among vaccinates and controls were similar and within average industry benchmarks for US pork production.

 

Study results demonstrated that Fostera Gold PCV MH and Fostera Gold PCV are safe for use in pregnant female swine in all stages of gestation, Zoetis said.


- Zoetis

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