How Do We Stop Overvaccinating? 
The use of serologic testing in the establishment of individual vaccination protocols
By Sarah Levine, VMD and Yaniv Dolev, DVM  

In the past decade vaccination schedules have come under investigation not only by the scientific world but by laypeople as well.  The veterinary profession is faced with the controversy revolving around “over-vaccinating".  Clients and colleagues alike are demanding answers to the probing question: Are we vaccinating too much?  

Accumulated data shows that vaccines given annually are not necessarily more effective. Challenge studies have proven that the immunity achieved by using CDV (canine distemper virus), CPV (canine parvo virus) and CAV (canine adenovirus) vaccination may last 7 years (1, 2, and 3).  Other challenge studies have proven that using a modified live vaccine for FPV (feline panleukopenia virus), FCV (feline calici virus), and FHP (feline herpes virus) results in a vaccine immunity that lasts 3-5 years (4, 5).  

Unnecessary administration of vaccines due to protective immunity that lasts considerably longer than one year, as well as the concern for adverse vaccine reactions (6), spurred some changes in vaccine protocols.  The American Animal Hospital Association (AAHA), The American Association of Feline Practitioners (AAFP), as well as USA veterinary schools recommend a triennial vaccine schedule for “core vaccines” (CDV, CPV-2, CAV-2, FPV, FVR, FCV and rabies) as long as the animal has received a good puppy/kitten series (7, 8).    

The New Recommended Vaccine Protocols:  

Serologic Testing:  
Until now, vaccine administration was a major service provided which was never evaluated.  Many practices have adopted the use of serology testing to insure that their patient’s antibody titers are sufficiently protective (1, 9, 10 and 11).  Protection against most viral diseases is antibody-mediated (8). Luckily we can easily measure antibody levels. The presence of antibodies is an indication of immunological memory and the ability of the animal’s immune system to respond to a given antigen (8).  Diseases in which titers are proven valuable include, but are not limited to: canine distemper, feline and canine parvo virus and canine adenovirus (7).   

Measuring antibody levels helps clinicians determine when it is optimal to start and stop the puppy vaccine series. In this way the veterinarian can modify vaccine programs for individual puppies.  Serology testing is useful after a dog/cat’s first series of vaccines to indicate whether immunization success was achieved (12).   

Serologic testing is important in adult dogs/cats as well (13). Serology testing can assist veterinarians to assess the immune status of patients with unknown vaccine histories. With   cases where immune stimulation during vaccine administration can lead to severe side effects, like for example an animal with a history of adverse vaccine reactions, immune mediated diseases, skin allergies, or an animal undergoing chemotherapy.  A positive serology test can help prevent unnecessary administration of vaccines and prevent possible relapses or exacerbation of existing conditions (7).  

Many agree that routine serologic testing is beneficial because it allows the identification of animals that do or do not require booster vaccinations (9). A clinician can determine when protective immunization in each puppy has been achieved.  This will allow the puppy isolation period to be only as short as necessary and thus socialization can occur as soon as possible (10).  Antibody tests can be used to determine the duration of immunity (DOI) acquired by either vaccines or from natural exposure (6).   Routine serologic testing can also provide data on the efficacy of various vaccines, timing for administration of vaccines, passive immunity, and persistence of immunity for companion animals (9). 
 
Individually Tailored Vaccination Protocols: 
Annual vaccinations have been the "bread and butter" of most veterinary practices.  Annual appointments for vaccinations allowed veterinarians the opportunity to inform clients of aspects in health care, promote new products, and diagnose problems early.  However, most clients came to believe that the vaccine was the most important reason for the annual visit.   

What is crucial now is to educate clients about the importance of a comprehensive health care program. Each patient’s vaccination status should be assessed yearly and modified according to age, lifestyle, changes in environment and titer values. This yearly "vaccination interview" should become part of the yearly health exam and may not necessarily be followed by an injection (9). Clients should be provided with newsletters and educational material that discuss specific diseases, vaccines, risk factors, and adverse reactions associated with vaccines (7).  

Biogal’s  New ImmunoComb^® VacciCheck: 
Biogal’s new VacciCheck kits allow veterinarians to vaccinate patients using an individual vaccination program rather than an automatic vaccination program.   

The ImmunoComb^® Feline Virus Vaccination IgG Antibody Test Kit measures IgG levels for Feline Panleukopenia Virus (FPV), Feline Herpes Virus (FHV), also known as Feline Viral Rhinotracheitis, and Feline Calici Virus (FCV).  These viruses are responsible for serious disease in unprotected cats and kittens.  This antibody test kit allows the clinician to check whether the kitten vaccine series achieved its goal.  The goal being: immunization and protection of the patient.  This test kit also allows the clinician to better monitor the duration of immunity achieved individually in each of his adult cat patients.  Thus, only those cats that require revaccination will receive vaccines.  

The ImmunoComb^® Canine VacciCheck Antibody Test Kit measures IgG levels to Infectious Canine Hepatitis (ICH), Canine Parvovirus (CPV) and Canine Distemper Virus (CDV).  These viruses cause serious disease in unprotected dogs and puppies.  This test kit allows the clinician monitor the IgG antibody levels of his patients and thereby determine when and if the puppy vaccine series administered conferred protection to the puppy.  In this way the clinician can halt the puppy isolation period as early as possible and begin socialization as quickly as possible. The kit can also be used during the yearly "well visit" to determine whether or not the patient requires revaccination.      

References:  
1.  Tizzard I Ni Y. Use of serologic testing to assess immune status of companion animals. J Am Vet Assoc 1998; 213:54-60.
2.  Gill M et al. Three-year duration of immunity for Canine Distemper, Adenovirus, and Parvovirus after vaccination with a multivalent canine vaccine. Intern J Appl Res Vet Med 2004; 2(4): 227-234.
3.  Abdelmagid OY et al. Evaluation of the efficacy and duration of immunity of a canine combination vaccine against virulent parvovirus, Infectious Canine Hepatitis Virus and Distemper Virus Experimental Challenges. Vet Ther. 2004; 5(3):173-86.
4.  Scott FW and Geissinger CM. Long-term immunity in cats vaccinated with an inactivated trivalent vaccine.  Am J Vet Res. 1999; 60: 652-658.
5.  Lappin MR et al. Use of serologic tests to predict resistance to feline herpesvirus 1, feline calicivirus, and feline parvovirus infection in cats. J Am Vet Med Assoc. 2002; 1:220(1): 38-42.
6.  Moore GE et al. Adverse events diagnosed within three days of vaccine administration in dogs. J Am Vet Med Assoc. 2005; 7:222(1): 1102-1108.
7.  Paul MA et al., 2006 AAHA Canine Vaccine Guidelines.  J Am Anim Hosp Assoc. 2006; 42(2): 80-9.
8.  2000 Report of the American Association of Feline Practitioners and Academy of Feline Medicine Advisory Panel on Feline Vaccines. J Feline Med Surg. 2001; 3(2): 47-72.
9.  Horzinek, M.C. Vaccine Use and Disease Prevalence in Dogs and Cats.  Vet Microbiol, 2006.
10. Twark L and Dodds WJ. Clinical use of serum Parvovirus and distemper virus antibody titer for determining revaccination strategies in healthy dogs. 2002.  J Am Vet Med Assoc. 2000; 7:217(1): 1021-1024.
11. Waner T et al. Assessment of maternal antibody decay and response to canine parvovirus vaccination using a clinic-based enzyme-linked immunosorbent assay. J Vet Diagn Invest 1996; 8:427-432.
12. Waner T et al. Assessment of immunization response to canine distemper virus vaccination in puppies using a clinic-based enzyme-linked immunosorbant assay. Vet J. 1998; 155(2): 171-5.
13. Waner T et al. Application of a dot enzyme-linked immunosorbent assay for evaluation of the immune status to canine parvovirus and distemper virus in adult dogs before revaccination. J Vet Diagn Invest 2006; 18(3): 267-70.