When commercial vaccines can't provide the protection needed due to a new, disease-causing agent or antigenic variations, many beef producers rely on their veterinarians to identify the problem organism(s) and have a custom (autogenous) vaccine manufactured to meet immediate needs.

"Custom vaccines are not something that can be used commercially because each vaccine is herd or feedyard specific," says D.J. Rezac, D.V.M. with Grand Laboratories, a division of Novartis Animal Vaccines, Inc. "The same vaccine cannot be sold to everyone because custom vaccines do something very specific for each farm or feedyard."

Often needs that stir the development of a custom vaccine are more widespread than just one herd or feedyard. Other producers face the same dilemma and want a similar vaccine. As a result, a custom vaccine sometimes paves the way for a commercial vaccine.

For example, Fusogard(R) Bacterin started out as a custom vaccine for the bacterium Fusobacterium necrophorum, the primary cause of footrot.

"Customers were asking for a product like Fusogard," states Gary Anderson of Novartis Animal Vaccines, Inc. (previously Imm Tech Biologics). "Thus, there was a niche and reasons for establishing Fusogard as a licensed vaccine. Also, the bacterium lends itself to a master seed much more readily than some of the other diseases. It's a more stable bacterium, it doesn't mutate readily, and very few unique strains are out there.

"Producers needed a way to fight this problem, and we provided it to them."

When manufacturing a custom vaccine, companies must demonstrate through lab tests that the vaccine is safe and sterile. However, to take a custom vaccine and turn it into a commercial product, licensure requires stringent efficacy testing.

Dr. Anderson explains that researchers often use experience gained with a custom vaccine to help design the challenge model for efficacy trials. It is this challenge model that helps the USDA review, test and perhaps approve the product as a commercial vaccine.

Protocols for studies must be submitted at least 60 days prior to the proposed initiation date of the study.

"Protocols for studies are rigid and encompass animal immunogenicity/efficacy, field safety, shedding of the organism, spreading of an organism and immunological interference as well as other areas," states Doug Burkhardt, autogenous vaccine and R&D manager for Biovet of Sibley, Iowa.

Protocol must state the specific objective of the study as related to the recommended use of the product; the age, breed, sex and any other features of animals used in the test; composition of the product; composition of the placebo administered to the control group; number of subjects per treatment group; and the method of randomly assigning treatments to subjects.

The USDA also wants to know the source, housing, management and observation of the subjects; methods to ensure blinding of clinical observations; and time periods during the study when different treatment groups are in contact or separated. Other items required to document and submit to the USDA are outcomes, explicit case definitions or scoring systems and the methods of data analysis.

Trials must involve a minimum of 30 animals that are divided into two groups. One group is vaccinated with the product, and animals in the other group serve as the control group and are given a placebo. Both groups are exposed to the organism, and each animal's response to the organism is evaluated.

Trial data must be carefully compiled, and submitted to the USDA.

A product license application also requires supporting data regarding label indications, routes of administration, species recommended, age and susceptibility of animals, onset of immunity, duration of immunity, passive immunity, and active and passive immunity.

In the case of Fusogard, the product met the stringent requirements of the USDA and was granted a full license. The time needed from start to finish for licensing: three years.

Burkhardt notes that taking a custom vaccine to conditional license to full licensure usually takes two to three years but can take up to five years depending on the product and the manpower dedicated to getting the job done.

While some individuals debate "which is better -- a custom vaccine or a commercial vaccine," Burkhardt is a proponent of custom vaccines for certain tough diseases.

"With custom vaccines, the 'bug' is current and that 'bug' is specific to a farm, ranch or feedyard," Burkhardt relates. "With commercial vaccines, the 'bug' sometimes is outdated before the commercial vaccine enters the market."

Burkhardt and Dr. Anderson agree that there is a place for both commercial vaccines and custom vaccines in the marketplace. Custom vaccines fill a void where effective commercial vaccines are unavailable, and custom vaccines are available much faster when diseases enter the agricultural sector. ©