September 15, 2004

 
CONVENTION COVERAGE

 The vexing vaccine issue - September 15, 2004

posted September 1, 2004
 

Controversy, confusion continue to surround vaccine guidelines

In recent years, the release of vaccine guidelines for dogs and cats has stirred up controversy in the veterinary profession and confused some veterinarians and pet owners.

"Veterinary medicine is truly going through some unprecedented changes. I think the vaccination environment is one of them," comments Dr. Richard Ford, a professor of small animal internal medicine at North Carolina State University College of Veterinary Medicine.

Dr. Ford was on the American Animal Hospital Association Canine Vaccine Task Force, which released its vaccination guidelines in spring 2003. These guidelines recommended three-year booster intervals in adult dogs for distemper virus, parvovirus, adenovirus-2, and parainfluenza virus.

"I have had so many veterinarians call and say, 'I don't understand the new vaccination protocols that have been published,'" said Dr. Ford, who spoke at the AVMA Annual Convention during an educational session. "The vaccination guidelines are neither standards for the profession—they are not regulatory—nor do they represent a protocol." According to Dr. Ford, veterinarians should look at the published guidelines as a tool to use when they are creating dog and cat vaccination protocols for their clinic.

This wasn't the first time that veterinarians saw "every three years" in vaccination guidelines. In 1998 and again in 2000, the American Association of Feline Practitioners published a report recommending vaccinating adult cats against panleukopenia virus, feline herpesvirus-1, and feline calicivirus, every three years, rather than annually.

Many veterinarians have responded to the three-year guidelines with resistance. "It was truly a bitter pill, and we did not take this well," said Dr. Ford, who is also brigadier general in the U.S. Air Force Reserve. "At issue here is that the bitterness of the pill prevails. Despite growing acceptance of the guidelines, there is still considerable resistance."

Veterinarians are resistant because, when one examines the services that veterinarians provide in the United States, Europe, and the United Kingdom, vaccination is at the top of the list for both cats and dogs. "Our paradigm has been challenged, and it is gradually shifting as we look at alternative ways to select and use vaccines," Dr. Ford said. According to him, the real resistance comes from a misunderstanding of the vaccine guidelines released.

"The resistance comes from the fact that the take-home message appears to have been 'vaccinate every three years.' That is not what we intended by writing these guidelines, but yet, that seems to be what people think, whether or not they have read the guidelines," Dr. Ford said. "None of us on those task forces for the cat or the dog have advocated that you only vaccinate every three years. We are asking you to consider which vaccines you are using every year."

The AVMA vaccine guidelines for dogs and cats released in November 2002 by the AVMA Council on Biologic and Therapeutic Agents also recommend tailoring vaccine programs. The "COBTA Report on Cat and Dog Vaccines" concluded that inadequate data exist to scientifically determine a single, one-size-fits-all protocol for vaccination or revaccination of dogs and cats. It said that variations among patients, their lifestyles, and related disease risks, and between individual vaccine products available, necessitate a customized approach to vaccination recommendations.

COBTA concluded that evidence shows that some vaccines provide immunity beyond one year. While annual vaccinations have been highly successful in curbing disease, the one-year revaccination frequency recommendation found on many vaccine labels is based on historical precedent, not scientific data. Even in cases where scientific data were submitted to qualify a label claim, the data generated generally represent a minimum duration of immunity and don't resolve the question about average or maximum duration of immunity.

While differences in the various guidelines exist, all recommend that clinics develop a core vaccine program, which includes vaccines that should be given to all dogs and cats that visit a clinic, and a noncore vaccine program. In determining whether a vaccine for a particular disease is core, veterinarians should consider the severity of the disease, the geographic location of a clinic, the risk of transmission to the animal, the potential for a particular infection to be zoonotic, and the performance of the vaccine.

Noncore vaccines are reserved for animals with unique needs because their lifestyle represents a reasonable risk of infection. Practitioners should establish which vaccines meet the definition of core in their locale and then communicate that information to all staff that work in a practice.

Dr. Ford said he knew of one practice that had 15 vaccine protocols, and this only caused confusion among the clients and staff. "Everyone in the practice needs to be on the same page with respect to which vaccines are core," he said.

In Dr. Ford's opinion, veterinarians have a responsibility to look at the guidelines. The vaccine protocol of individual practices is at stake, vaccine safety is at stake, and unprecedented changes are occurring in vaccine technology, such as the introduction of recombinant vaccines.

He points out that veterinarians practicing in the United States can no longer report adverse vaccine events to the U.S. Pharmacopeia's Veterinary Practitioners' Reporting Program. Funding was discontinued last year and the program ended in April 2003. "Today, there is no national database through which veterinarians can both report adverse drug/vaccine reactions and obtain adverse event information pertinent to a particular product," Dr. Ford said.

While veterinarians should report adverse events to the manufacturer or the Department of Agriculture's Center for Veterinary Biologics, there is no database of information that can be used for an epidemiologic study. This is unsettling for researchers studying vaccine adverse events such as vaccine-associated sarcomas, which Dr. Ford says occur in somewhere between one in 10,000 and one in 1,000 vaccinated cats. Either is unacceptable.

"This could be a train wreck for our profession," Dr. Ford commented. "For over 10 years, we have known there is a cause-and-effect relationship between vaccination and fibrosarcoma in some cats. There is no evidence today that, in the past 10 years, we have succeeded in decreasing the incidence."

He encourages veterinarians to consult the published vaccine guidelines. Annual examination is still good medicine and should not be driven by the perceived need to administer annual boosters. Annual examinations are fundamentally important in the early detection of cardiac and dental disease, cancer, and many other conditions. Some veterinarians, who may be abiding by corporate policies, recommend that every dog and cat receive every vaccine every year. This is a blatant example of overvaccination, he said.

"That is absolutely incorrect and sets a bad precedent," Dr. Ford emphasized. "It is important to understand that guidelines are in place for the profession to use in developing a rational vaccination policy for the practice and the patients we're charged with caring for."