Effects of Vaccines

Thomas D. Overbay, DVMExpedite

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

• 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

• 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

• Viral • Bacterial• Protozoal• Fungal• Parasites

Types of Veterinary Vaccines

• 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

• 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– 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

• 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