Introduction

• There are historical reasons why the current vaccination strategy developed - often relating to the demands of the veterinary profession.
• Multivalent vaccines were developed to provide concurrent protection against infectious diseases.
• Annual booster vaccination schemes were first introduced to simplify the revaccination schedules.

• Many of the problems associated with the current datasheet recommendations for vaccine use stem from the vaccine licensing procedure.
• In most cases risk-benefit analysis is performed to establishthe overall usefulness and requirement for a new product.
  One drawback of this approach is that there is still little quantitative information on the prevalence of infectious disease in domestic pets.
• It is recognized that vaccination may be less effective in the field situation than under laboratory conditions.
• The regulatory authorities ideally require that duration of immunity claims are substantiated by laboratory and field trial data.
• By its nature, producing data for long term immunity is time consuming and technically problematical. For example Home Office regulations make it difficult to isolate animals older than 1 year. Most manufacturers have compromised by providing data only to support a one year duration of immunity claim.
  In fact, challenge studies (to demonstrate level of protection) are usually carried out within a few weeks of the last vaccine dose.
• The one year efficacy data is derived from demonstration of 'adequate' antibody titers and challenge studies (although the challenge model can be difficult in older animals).

• Most vaccines are multivalent (containing many different antigens) and the duration of immunity claim has to be based on the shortest duration of immunity provided by any of the components.
  The one year claim is therefore an absolute minimum duration of action for the product.
• In some cases duration of immunity is unknown and therefore, for example, although the current recommendations are for annual revaccination with FeLV or injectable parainfluenza vaccines, there is poor evidence for duration of immunity.

Booster vaccinations - do pets need them?

How often do we need to vaccinate?

What else can be done?

What should the veterinary profession be doing?

The Future

Further Reading

Publications

Refereed papers

• Recent references from PubMed and VetMedResource.
• Gaskell R M, Gettinby G, Graham S J et al (2002) Veterinary Products Committee working group report on feline and canine vaccination. Vet Rec 150 (5), 126-134 PubMed.

Other sources of information

• Greene C E & Appel M J (1998) Canine distemper. In: Infectious diseases of the dog and cat. 2nd edition. Ed C E Greene Philadelphia, W B Saunders pp 9-22.