December 23, 2003


Schering-Plough Unveils First Trivalent SIV Vaccine


Schering-Plough Animal Health Corporation, a United States pharmaceutical company, unveiled the industry's first trivalent vaccine for the costly swine influenza virus (SIV).

MaxiVac® Excell™ 3, a killed-virus vaccine, protects against all major strains of swine flu virus (SIV) circulating in the U.S. swine population. It features a new variant or "reassortant" strain of the H1N1 subtype in addition to the classical H1N1 subtype that has been circulating in U.S. hogs for decades.

The vaccine also contains an H3N2 subtype that protects against the Cluster I Texas-like H3N2 subtype, as well as cross protects against the Cluster III variants of H3N2.

"MaxiVac Excell 3 fills an unmet need and gives the pork industry a new tool for managing SIV," says Luis Fernandez, DVM, senior product manager for swine products at Schering-Plough Animal Health Corporation. "No vaccine provides broader flu protection against the most predominant strains in U.S. swine herds."


Trials Show Protection


Recent trials showed the significance of vaccinating for classical and reassortant H1N1 viruses. According to Fleck, pigs vaccinated with a vaccine containing only cH1N1+H3N2 were not protected when challenged with rH1N1. However, pigs injected with a vaccine containing rH1N1 had a statistically significant reduction in lung lesions after rH1N1 challenge, compared to unvaccinated controls and pigs injected with the cH1N1+H3N2 vaccine.

In another study, pigs were vaccinated twice 2 weeks apart with MaxiVac Excell 3 (cH1N1+rH1N1+H3N2). From 3 to 4 weeks after the second dose, they were challenged with either virulent rH1N1 or cH1N1. After 5 days, they were necropsied and their lungs were scored. MaxiVac Excell 3 significantly reduced lung lesions, as well as the percent of pigs positive for virus recovery from the lung tissue after both types of challenge. "The results demonstrate excellent efficacy, with no interference between antigens," Fleck says.

Pigs vaccinated with MaxiVac Excell 3 also showed significantly less nasal shedding of rH1N1, she says. Nasal swabs were collected daily from pigs after rH1N1 challenge and until necropsy. Overall, there was a 98.6% reduction in nasal viral titer during the 5 days after SIV challenge in pigs vaccinated with MaxiVac Excell 3, compared to unvaccinated controls. The difference was statistically significant.

"A reduction in nasal viral shed means less virus on the farm and a lower overall SIV challenge for all animals in the herd," Fleck says.


Proven Safety in Pigs, Breeding Stock


The strains in MaxiVac Excell 3 have been carefully selected and balanced for optimum performance. Because the vaccine contains Emunade®, the same proprietary adjuvant used for many years in the company's M+Pac® mycoplasma vaccine, MaxiVac Excell 3 can be used with confidence in sows or pigs with virtually no reactions or performance setbacks, according to Fleck.

MaxiVac Excell 3 is approved for use in pigs 5 weeks of age or older, including boars and pregnant sows, as an aid in the prevention of disease associated with the SIV subtypes rH1N1, cH1N1 and H3N2. The vaccine also has been shown to reduce pneumonia and lung infection following challenge. Schering-Plough Animal Health recommends vaccinating healthy pigs with a 2 mL intramuscular (IM) dose and revaccinating 2 to 3 weeks later.

"It's best to consult with your veterinarian for optimum vaccination timing to avoid interference with maternal antibodies from vaccinated sows," Fleck says.