Effects of Vaccines
Thomas D. Overbay, DVM
Expedite
Expedite
• Animal Health Business Development Company
• Focused on bringing new technology from
conception to commercialization
• Serving large, multinational companies as well
as start-ups and public/private partnerships
What are we going to talk about?
• Vaccination
• Vaccines
• Adjuvants
• Adverse Events
“It is not the things I don’t know that bother me;
it’s the things I think I know that turn out to be
wrong that keep me up at night”
The purpose of vaccination is to
stimulate immunity against
disease
It is an active process that requires
active participation by the calf and is
not without some risk
Health—Balance Between
Resistance and Exposure
Why Do We Vaccinate?
• The only reason to vaccinate is to produce an
economic benefit
• Sickness and Death Loss
• Production losses
– Weight gains
– Feed Efficiency
– Interest costs
• Reproductive efficiency
• Colostral immunity
What Vaccines Do Not Do?
• Vaccines do not cause disease
• Vaccines do not treat disease
• Vaccines do not work immediately and may take
multiple doses
• Keep in mind that there is no immunity in any
vaccine sold by any company—the immunity
comes from the animal
What Constitutes a Veterinary
Vaccine
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Product
Personnel
Facility
Subject to additional restriction by state or
other such authority (Johnes vaccine)
• All are approved by the USDA
Veterinary Vaccine Categories by
License
• Fully Licensed
• Conditionally Licensed
• Autogenous
Requirements of a Fully Licensed
Veterinary Vaccine
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Safety
Purity
Efficacy
Potency
Immunogenicity and antigen blocking
Vaccine Components
• Antigen (Ag)
• Carrier / Vehicle
• Adjuvant
• Preservatives
• Buffer Systems
Autogenous Veterinary Vaccines
• Approved in circumstances where a specific and
immediate need exists
• An approved veterinary vaccine is not effective in
preventing the disease
• An approved veterinary vaccine is not available to
prevent the disease
• Requires a specific diagnosis
• Limited to use on the farm or premises of
diagnosis
• Requires regular isolation and update
Types of Veterinary Vaccines
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Viral
Bacterial
Protozoal
Fungal
Parasites
Types of Veterinary Vaccines
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Whole killed organism
Modified Live organism
Live organism
Subunit
Recombinant
DNA
So How Do We Get Vaccines To
Work??
Immunizing the Animal
• Body must recognize the antigen as foreign
• Immunization requires exposure to a defined quantity of
antigen over a period of time
• Adjuvants play a role in both antigen recognition and
durability
• Immunization is an active process and is not innocuous
What About Adjuvants?
Adjuvants
• Adjuvant literally means “aid”
• Serve to enhance the immune response after vaccination
• Discovered “by accident” when animals with post-vaccinal
abscesses were found to have higher titers
• First adjuvants were inflammatory agents
• Later Fruend’s Complete Adjuvant was introduced
– Mineral oil
– Water
– Mycobacterium
Adjuvant Categories
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Aluminum salts
Oil emulsions
Polysaccharides
Proteins
Liposomes
Carbohydrates
Saponins
Cytokines
Bacterial derivatives
Choice of Adjuvant
• Not all antigens respond to adjuvants in the same manner
• Base on understanding of the protective immune response to
natural disease
• Multivalent vaccines are evaluated in approval studies
• Use of multiple vaccines at the same time is not evaluated
• Constitute a risk:benefit decision
• Benefits
– Greater resistance for longer period
– Vibrio vaccines as an example
• Risks
– Loss of productivity
– Enhanced inflammation or reactivity
– Greater incidence of adverse events
Choice of Adjuvant
Dependent upon:
• Animal species
• Specific pathogen
• Vaccine antigen
• Route of administration
• Type of immunity needed
Role of the Adjuvant
• Adjuvants vary in their function
• Mechanisms of action
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Create inflammation at the site of injection
Attract immune mediating cells to the site of injection
Orient the antigen in a specific geometric orientation
Influence the type of immune response
Influence the degree of immune response
Potential Adverse Events
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Fever
Lethargy
Anorexia
Arthritis
Myalgia
Allergy
May be exacerbated by antigen combinations (gram negative
bacteria) or stage of animal development (pubescent
Holsteins)
• Differentiate between reactions “from” vaccines versus those
“to” a vaccine
Strategies to Reduce Adverse
Events
• Time vaccines to periods of low stress
• Design vaccine program to minimize simultaneous use of
more “reactive” vaccines
• Design strategic vaccination programs
• Recognize breed tendencies toward reactive periods
Effects of Vaccines
Questions and Discussion