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PRODUCT NEWS: Merck Updates Equine Flu Vaccines


Prestige vaccines now meet current OIE and AAEP guidelines for clade 1 and clade 2 equine influenza virus strains.

Because equine influenza experiences antigenic drift—minor molecular changes in the virus as it passes among hosts—vaccines should be updated regularly to ensure protection against new strains. To this end, Merck Animal Health has announced an update to its line of Prestige vaccines.

The updated vaccine line now includes Florida ’13 of the clade 1 family and Richmond ’07 of the clade 2 family. Clade describes recently isolated virus strains that belong to the same family.


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Clade 1 circulates primarily in the United States, while clade 2 circulates primarily in Europe. “While we have not had any outbreaks of clade 2 in the United States to date,” said D. Craig Barnett, DVM, director of equine veterinary professional services for Merck Animal Health, “US horses competing internationally should have clade 2 protection on board.”

With the addition of these 2 new strains, Prestige vaccines now meet the current World Organisation for Animal Health and American Association of Equine Practitioners guidelines for clade 1 and clade 2 strains.

Dr. Barnett said the company has been monitoring influenza through the Merck Animal Health Biosurveillance Program, which helped researchers identify and isolate the Florida ’13 strain from a 2013 Ocala, Florida equine flu outbreak that impacted horses around the world.

Merck offers a breakdown of the newly named line of Prestige FluVac vaccines:

Disease Antigen

Current Product

New Prestige Product

EIV, EHV 1+4

Prestige II

Prestige 2


Encevac TC-4

Prestige 4


Prestige V

Prestige 5


Prestige V+WNV

Prestige 5+WNV


Prestige V+VEE

Prestige 5+VEE

“This launch is a testament to our commitment to the science of healthier animals,” Dr. Barnett said, “and we’ll continue to work to identify threats and deliver advanced vaccine solutions to help improve the lives of horses.”

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