Guardian® Now able to Provide Six-Month Immunitry For E.Coli

US - Intervet/Schering-Plough Animal Health have announced they have received USDA approval of an important label extension for its Guardian scours prevention vaccine.
calendar icon 10 September 2009
clock icon 3 minute read

MSD Animal Health - NYSE:MRK

The new label approval affirms that Guardian provides six-month duration of immunity (DOI) for E. coli K99 protection. This positions Guardian as the only multi-valent bacterial and viral combination scours vaccine with six-month DOI for E. coli – the longest proven DOI on the market.

"Scours is estimated to cost the beef industry hundreds of millions of dollars annually," says Dr. Kevin Hill, Technical Services Veterinarian for Intervet/Schering-Plough Animal Health. "And E. coli is one of the most lethal bacterial agents causing calf scours. The new Guardian six-month E. coli DOI claim means beef producers can vaccinate with a high level of confidence knowing that Guardian will provide E. coli protection as early as 6 months prior to calving, reducing the need for inconvenient vaccination and handling during late-term pregnancy."

Impact of calf scours

Guardian provides six-month duration of immunity (DOI) for E. coli K99 protection

Neonatal diarrhea – or scours – is a symptom of infectious viral, bacterial or parasitic intestinal infection and is documented as the most common reason beef calves become sick and die. Escherichia coli bacteria – or E. coli – are ubiquitous and capable of causing severe diarrhea and death within the first week of a calf’s life. Economic losses come not only from calf mortality and treatment costs, but also from decreased weight gains in the surviving calves.

Sound management practices, including vaccination and environmental management, as well as ensuring calves receive adequate colostrum within the first 2 to 6 hours of life, can greatly reduce the incidence of scours. Administering a scours vaccine, such as Guardian, to pregnant cows and heifers helps transfer scours protection to the calf via antibody-rich colostrum.

The Guardian six-month E. coli difference

According to Dr. Hill, efforts to achieve the new Guardian six-month E. coli DOI claim were successful for two primary reasons: the advanced sub-unit E. coli technology and a unique sustained-release adjuvant.

He explains: "The K99 E. coli antigen in scours vaccines stimulates the production of protective antibodies, which is what we want. However, the E. coli cell wall is a source of dangerous endotoxin (bacterial toxin). The new Guardian production process (sub-unit technology) harvests only the K99 pili, and eliminates most of the cell wall material, thus providing a clean, more concentrated level of the vital K99 antigen. Sub-unit technology reduces exposure to potentially dangerous sources of endotoxins that can lead to adverse reactions. In addition, sub-unit technology provides a strong and extremely targeted E. coli immune response."

Dr. Hill says coupling the Guardian sub-unit technology with its smooth, water-in-oil adjuvant translates into a safe, targeted and long-lasting immune response.

"Traditionally, water-based adjuvants are less reactive, and oil adjuvants are longer lasting. The custom formulated water-in-oil adjuvant in Guardian provides the best of both worlds. It is long lasting with low reactivity."

Most complete scours protection

Guardian is a broad-spectrum scours vaccine for use in healthy pregnant cows and heifers that protects against the most relevant viral and bacterial causes of scours. It is labeled as an aid in the prevention of neonatal calf diarrhea caused by enterotoxigenic E. coli pilus type K99, bovine Group A Serotype G6 rotaviruses, enterotoxemia caused by Clostridium perfringens types C and D and as an aid in the control of neonatal calf diarrhea caused by bovine coronaviruses.


Guardian administration consists of one 2-mL subcutaneous dose for annual revaccination. It is the only scours vaccine on the market labeled for subcutaneous administration, meeting Beef Quality Assurance guidelines.

"The fight against the costly effects of calf scours continues, but producers now have another tool in their scours-management toolbox," says Dr. Hill. "The new six-month E. coli DOI is just one more way Intervet/Schering-Plough Animal Health is advancing calf health and productivity."

Producers are encouraged to work with their veterinarians to design a calf scours management program appropriate for their herds.

Guardian is available through veterinarians or animal-health suppliers. For more information about Guardian, or to learn more about Intervet/Schering-Plough Animal Health’s full line of innovative, high-quality cattle health products, visit or

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