To see NEW--EMERGING TRENDS IN VACCINATIONS-2008, click here.
To see the latest in the AVMA/AAHA (2006) recommendations for vaccines, click here.
To see UCDavis 2007 Vx recommendations, click here.
To see Colorado State's new vx recommendations, click here.
To see WSU's 2008 Vx Chart, click here.
2004: EMERGING TRENDS IN VACCINATION PROTOCOLS
MODERATOR: Hugh Lewis, BVMW, MRCVS, DACVP
PARTICIPANTS: John Eliis, PhD, DACVP, DACVM; Kathy Endler, DVM, DABVP; James Evermann, MS, PhD; Karen Faunt, DVM, MS, DACVM; Larry Glickman, VDM, DrPH; Steven Levy, VDM; Will Novak, DVM, MBA, DABVP.
"Leading experts examine the purpose of vaccination, its benefits, and current practices. They also discuss emerging trends in vaccination protocols, including the safety and efficacy of a new canine vaccine with three-year duration of immunity challenge data."
INTRODUCTION:
Lewis: When I was reading the April 1, 2004, issue of JAVMA last night, it seemed prescient that the first letter to the editor is titled "Calls for Vaccine Challenge Studies."....Today we will talk about that very subject. Let's start by examining some preventive care and vaccination basics.....I think it's important to understand pet owners' perspectives of what they want for their pets....they want their pets to be happy, and long-lived. To deliver this, veterinarians must emphasize preventitive care, and vaccination is a central component (of that).
PURPOSES OF VACCINATION:
Lewis: Let's discuss the purpose of vaccination. We'd all agree it's an effective means of disease prevention. It's cost-effective, and it's far better to protect a pet from disease than to wait and treat the disease itself....vaccination also decreaes the prevalence and risk of disease in the pet population as a whole...& can also prevent pets from becoming a zoonotic threat to family members...
Novak: Vaccines have been so successful in preventing disease that many veterinarians think these diseases don't exist anymore...A key point is vaccines have been successful...because they have been widely used.
Eliis: I would echo the importance of herd immunity. I am concerned about the tendency...[of] studies to suggest that duration of immunity, at least for some vaccines, is more than one year. I do not think these studies constitute a basis for change, because they cannot address....herd immunity....I am concerned about changing protocols that have worked so well historically....
Levy: I agree that group immunity is important....Before I would change my protocols, I'd want to see challenge study data to determine whether there is a reason to change....I'm worried about the protective barrier that keeps disease from spreading.
Glickman: There are two distinct aspects of immunity--clinical protection and prevention of shedding.
Faunt: In our practice we still see parvovirus infection and distemper.
Glickman: We just completed a serologic study of mature Great Danes. We studied three categories: those that weren't vaccinated because the owners believed in holistic care, a group that was vaccinated as puppies and never vaccinated again, and the more traditional group that was immunized as puppies and then vaccinated yearly....[our research] confirmed parvovirus is prevalent in the environment, and dogs are likely to be infected...subclinical infections also exist, but you wouldn't know about it unless you did a study like this....[so it is] also a warning to be careful when interpreting titers.........
Levy: I'd like to make two more points. First, some dogs may have been infected with parvovirus and died, so they weren't in your groups. Also, antibody titers don't always indicate protection.
BENEFITS OF VACCINATION:
Lewis: I think we are on the same page when it comes to the purpose behind vaccinations. It leads us to the next question: when should we vacccinate?
Everman: There are two benefits to vaccinations. The first is protection of the individual dog from developing a serious, life-threatening disease. The second is to determine shedding of the infectious agent....that is why it's important to determine the risk category that the dog is in when preparing the vaccination program. Each dog is different..........I'd argue that measuring serum antibody titers can be beneficial, but one must intepret the results with caution....[using] a protection threshold of 1:100 or greater for both canine distemper virus and canine parvovirus....
Novak: Vaccination is the only practical way we can protect pets from these lethal infections.
Engler: ....we also have to consider...the pet-family bond. A pet getting sick and dying from a preventable disease is unacceptable...if we don't protect pets against a disease....we have failed the pet and the family....
Levy: Ideal owners value their pets as family members.....it's a reason to give them maximum protection. It's an injustice to not offer something as effective and inexpensive as a vaccination--especially if it's not offered because of a misconception about either incidence of disease or duration of immunity. As Dr. Glickman said, those Great Danes were exposed to parvovirus....I don't want to see another case of parvovirus in my lifetime. THE low incidence of disease or the impression there is no disease is proof that vaccines are working.
Lewis: We have done a survey of distemper cases over the past two years....we found 3,136 cases of suspected distemper (out of a population of 2.1 million dogs)....
HEPATITIS AND PARVOVIRUS INFECTION:
Lewis: Next, let's talk about hepatitis and parvovirus infections. Are we still seeing those diseases?
Novak: As Dr. Glickman mentioned, parvovirus infection is a persistent problem. If we didn't vaccinate for it, the number of cases would likely increase dramatically.
CORONAVIRUS INFECTION:
Everman: I'm an advocate of using coronavirus vaccines in high-risk puppies and their dams. The concept of core vaccines implies importance, and noncore means not important. This is misleading, since canine coronavirus...can cause mortality in puppies...
Ellis: In the recent Executive Summary and 2003 CANINE VACCINE GUIDELINES AND RECOMMENDATIONS, the AAHA task force suggested in the case of diseases that are of little clinical significance....vaccines [are] not generally recommended. The idea that treatment is preferable to prevention seems inconsistent with increasing concern about the overuse of antibiotics....[and} certainly we should be concerned about preventing severa or fatal disease, but also about reducing morbidity and improving quality of life. IF we can do that through vaccination, as opposed to treatment, I think vaccinations are preferable.
Faunt: I agree. Just because you can treat a condition doesn't mean you should not prevent it.....just because a condition isn't lethal isn't a reason not to prevent it if you can.
Novak: ...when dogs were coinfected with parvo [& corona] virus, the mortality rate increased...to 89%. This shows combination infections are of great concern....we cannot look at each one of these conditions in isolation.....
Levy: The [AAHA] idea we shouldn't be bothered to prevent a treatable condition is a terrible one.....this brings me to the notion of core vs. noncore vaccines. This is a bad notion because it eliminates epidemiology...We cannot ignore vaccines just because a disease seems to have an isolated range. Those ranges tend to expand...
Novak: According to the U.S. Census Bureau's report on geographical mobility for 2002-2003, 14% of all Americans move every year, and 40% take their pets on vacation....so the idea of a regional disease or regional exposure is suspect........clients expect us to protect their pets.....
Levy: My goal is to protect every pet under my care maximally. Vaccinations certainly haven't failed me yet, and I do not see it causing problems. To change the protocols I've used successfully for 27 years is a big step and will require convicing scientific data.
Engler: Dr. Levy brings up a good point about protecting the pet against chronic disease sequella...that can weaken the pet family bond and diminish the pet's quality of life.
Lewis: Dr. Glickman, I am not sure you agree with this.
Glickman: I have a problem with a comprehensive policy of vaccinating all pets for every disease we can....Your argument seems to be that if we fail to vaccinate a pet for everything, then we haven't provided maximum protection....Is that what you are saying?
Levy: It may have sounded like I vaccinate every dog and cat for everything, but I do, in fact do risk accessment. For example I don't administer feline leukemia vaccines to cats that don't go outside.....Ellis: I certainly don't advocate vaccinating every animal with every antigen. What Dr. Levy alluded to is the profession has done a good job of risk assessment without much direction and in the absence of data....What we have been doing has worked. So that is still my concern: changing from a protocol that works to a protocol that we're not sure will work, such as extended intervals between vaccinations.
Lewis: One issue that bothers me is how we, as a profession, sometimes make sweeping judgements and changes in the absence of adequate evidence. Our practice data suggests that, if a disease is endemic in one part of the country, then we see it almost everywhere...we have heard so many clinicians say "It doesn't happen here," and suggest that even testing for the disease is innappropriate. We must stop thinking this way.....
Ellis: That's an excellent point.
Novak: One question is whether we can assess risk and change vaccine schedules....how feasible is it [to determine the individual risk assessment[ in the exam room? [Our clients] expect the pet to be protected from preventable disease...
Engler: I think leptospirosis is a good example. A lot of veterinarinas have stopped vaccinating because they don't think they see it in their regions. Yet if you look at the literature over the last four or five years, veterinarians are finding more and more lepto....Dr. Glickman noted that when he lectures about lepto...veterinarians start finding it.
Levy: That's a perfect example of if you don't look for a disease, you will never find it. It we are doing anything, we should be doing more surveillance...
LEPTOSPIROSIS AND LYME DISEASE:
Lewis: In terms of risk assessment, one of the important elements has to be the risk posed by the vaccine. Some vaccines, especially those developed for bacterial diseases, have a reputation for producing a higher incidence of adverse reactions, and many veterinarians avoid using them. In fact, many dog breeders do not vaccinate against leptospirosis and Lyme disease. Are adverse effects a big issue?
Levy: There is no major safey issue proved to be associated with the original Lyme disease vaccine. Our 1993 JAVMA article is a safety and efficacy study involving Lyme disease vaccine...we found only minor adverse reactions......
Lewis: Dr. Glickman, you have had experience with leptospirosis--would you talk about adverse effects?
Glickman: Yes, we have to be cautious about dismissing reports of adverse effects....because...we don't have a well-developed, formal postmarketing surveillance system....The bottom line is we don't have sound scientific data about the frequency or pattern of adverse reactions....
Levy: You recently published a study in JAVMA on what appears to be a resurgence of leptospirosis. Does this reflect lack of vaccination or lack of vaccination against emerging pathogenic serovars?
Glickman: The resurgence we've seen in the incidence of leptospirosis among dogs since 1991 or 1992, particularly with L. pomona and with L. grippotyphosa, is not likely due to low vaccination rates...there has been a true reemergence of canine leptospirosis associated with new serovars, possibly due to changes in wildlife ecology...This is why I think leptospirosis vaccines containing new serovars are so important now in controlling or reducing the rate of Leptospirosis infection in dogs.
Lewis: So the cases we are seeing reflect infection with different serovars...?
Glickman: Absolutely.
Lewis: So leptospirosis is a big problem....
Glickman: There are practioners who..will see one or two reactions and not use the vaccine anymore.
Lewis: That's right. Clients or veterinarians sometimes have a negative attitude toward vaccinations....whereas, in our own experience, we have seen reactions, but they are relatively uncommon. We know how to deal with them, and it isn't a significant issue for us as a practice.
Levy: It factors into the entire risk-benefit assessment...I think the risk of being exposed to the diseases for which we are vaccinating far outweigh the risk of vaccination.....
Glickman: We know that all vaccines may cause adverse reactions, both mild and severe,....the rate of expected adverse reactions should always be factored into a risk assessment. Despite this, the generally acceptable guideline is that all dogs should receive certain core vaccinations, such as those for rabies, distemper, and parvovirus infection. I think that is the right thing to do as a veterinary community. We have the obligation to say that every animal should receive vaccinations for rabies, distemper, parvovirus infection, and whatever else we believe is core for dogs based on the doog of the general dog population.......
Novak: That's a good point. I don't think the veterinary profession has evaluated national risk assessment with all the factors that need to be included--it has been too narrow in scope.
Glickman: I have tried to create a generalized risk assessment that can be used for all canine and feline vaccinations. But if the process is too detailed, it becomes impossible to do on a case-by-case basis.....on the other hand, if you design a simple process that provides realistic risk assessment, some people criticize it, saying it's not detailed enough....
GIARDIA INFECTION:
Levy: I'm going to speak now as the average small animal practitioner--I know so little about Giardia infection that I'm not sure what to do. I tested 67 dogs from the police canine unit and found that ALL of the dogs acquired from Czechoslovakia were infected with Giardia, as were the dogs housed with them....so where do we go for the information [we need] so we can make our risk assessment?
Lewis: Good question. Should we be vaccinating for giardiasis?
Faunt: In our own study, we tested 17,500 pets for Giardia infection and up to 13% tested positive....this study involved hospitals acorss the country in both urban and suburban areas. Two-thirds of the infected pets were asymptomatic, but shedding into the environment, and possibly infecting other pets. Giardiasis is also potentially zoonotic. You are right, most practioners don't know the prevalence of Giardia infection in their regions. Only 16% of the ELISA-positive pets actually tested positive using fecal flotation. So if practitioners do the wrong test, they don't detect infection.
Engler: And the area with the highest infection rate....was actually downton Kansas City....
Lewis: We must remember that Giardia species have zoonotic potential..........
Levy: I wonder how many cases of giardiasis I treat without knowing it. My standard therapy for a dog with diarrhea includes metronidazole--I know that this drug is an effective gastrointestinal anti-inflammatory. But perhaps any dog on metronidazole therapy should be tested. I should know if the pet has giardiasis or not.
Faunt: Absolutely. That's important because if you are treating with metronidazole, you may eliminate the clinical signs, but not the infection.
Novak: I read that one-third of Giardia cases are resistant to metornidazole now. Therefore prevention by vaccination is a better approach than treatment.
Levy: I'd like to ask a question about disease prevention. What is the threshold incidence level warranting a prevention program?
Lewis: It's an interesting question. When do you prevent something? DO you wait for it to become endemic or do you try to prevent that from happening?
Glickman: You have to look at each disease individually. For a disease like Lyme, we won't decrease transmission by vaccinating dogs, but it is different for parvovirus. By vaccinating against pathogens like parvovirus, we aim to produce herd immunity. So there is no one answer--each disease is different.....
Ellis: That brings up an interesting point about the need for vaccinations at different life stages....
Glickman: You might be surprised that most puppies don't come from puppy mills or pet stores. The vast majority (over 70%) of owners buy from a person who had had a litter in his home or from a breeder, or the owners bred the dog themselves...Thus, many of the dogs producing puppies that are purchased by new owners will be dogs that you probably do have an opportunity to see in your practice and for which you can provide preventative medicine to reduce the incidence of infectious disease and parasitism. We hear a lot about puppy mills, shelters, and pet shops, but they account for only a small portion of new animals....
BORDATELLA INFECTION:
Lewis: What about Bordatella infection? Should we be vaccinating for kennel cough?
Everman: Bordatella and parainfluenza virus are both short-lived immunogens. They rely on IgA mucosal immunity for maxiumum protection and should be given twice a year in high-risk situations, such as boarding.
Novak: Dr. Glickman, you did a study on Bordatella infection, right?
Glickman: Yes. There are only two published field studies that I know of on the efficacy of the intranasal vaccine to prevent kennel cough. We published one of the studies in 1981 and the other one more recently. I deal with kennel situations where risk of transmission of organisms that cause kennel vough is most intense. Without vaccination in these environments, you can expect a 10% to 50% incidence of kennel cough.....based on our studies, the intranasal vaccine is the most effective vaccine for the shelter or kennel environment. It will not prevent all kennel cought because the disease is caused by a variety of bacterial and viral agents... I think you need a good intranasal Bordatella vaccination program whenever you have a high density of dogs.....it is more important in some environments than others, but all dogs should receive the intranasal vaccine at least yearly to prevent kennel cough.
THREE-YEAR DURATION OF IMMUNITY CHALLENGE DATA:Lewis: We've had a good general discussion about vaccinations, so let's move to the next topic, which is DURAMUNE ADULT, the Fort Dodge new vaccine offering a three-year duration of immunity for distemper, hepatitis, and parvovirus. Dr. Novak will review the results of the challenge study. Then we will talk in depth.
Novak: I'll give an overview of the challenge study, which was done to license the vaccine. The three components of the vaccine are distemper virus, adenovirus, and parvovirus antigens. For the distemper virus segment of the study, five dogs were given intramuscular vaccine, nine dogs were given subcutaneous vaccine, and two dogs were controls. For parvovirus, five dogs were given intramuscular vaccine, five dogs were given subcutaneous vaccine, and three dogs were controls. The study was performed over a three-year period. At the end of the study, the vaccinated groups were challenged with the virus for which they were vaccinated. The controls in the groups were challenged with the same virus. In the distemper group, the vaccinated dogs either remained healthy or showed mild or transient signs of disease. The unvaccinated controls experienced severe illness, and two of the three died. In the adeonovirus group, the results were similar. In the parvovirus group, all the vaccinated dogs once again established good protection. Two of the dogs experienced mild vomiting at the peak challenge period. Unvaccinated controls showed moderate to severe signs of disease. The study appears to demonstrate protection for distemper virus, adenovirus, and parvovirus when vaccinated dogs are challenged after three years. The controls appear to have been severely affected by the challenge, demonstrating that the challenge process was adequate.
Engler: And the researchers did measure titers as well to ensure that the controls had not been exposed to the infectious agent before the challenge.
Levy: Did the researchers measure titers on the vaccinants before they were challenged?
Engler : They did.
Levy: And did the vaccinants have circulating antibodies?
Lewis: Yes. It was on the basis of the challenge study that the USDA approved the vaccine.
Everman: I'm pleased to see the generation of long-term immunogens into the adult vaccination programs. I have advocated this for a number of years...
Glickman: To be licensed, a vaccine must show purity, potency, efficacy, and safety. The efficacy of the new Ft. Dodge vaccine is apparent to me from the data we reviewed, but we cannot determine safety based on this study. Usually new vaccines must also be tested for safety by practicing veterinarians using pet dogs. The usual tests would involve 400 to 600 dogs that are vaccinated and then followed in the office and at home for possible reactions after vaccinations.
Novak: The hypothesis is that the safety profile would be similar to that of the current distemper combination vaccines.
Lewis: The antigens in this vaccine have been used in marketed vaccines for many years....they are identical.
Glickman: It may be the same antigen, but there may be other important issues. When the antigen concentration increases in a vaccine, so might the concentration of foreign proteins.....
Ellis: I don't think a 13-dog study is proof of efficacy in the larger population. The only thing that will constitute proof for me is if everyone used the three-year vaccine, and we evaluate the results.
Lewis: I think the study shows efficacy, but it is not the same thing as efficacy in the field.
Ellis: I certainly agree that this study demonstrates efficacy in relevant challenge models, but the problem is making this, or simlar studies, the basis for major changes in protocols that have worked in the field at the population leve. That is because such experimental infections can't encompass all of the variation that determines vaccine efficacy in the field.
Levy: The reality is that even though I've heard people saying that only 5% of our colleagues are switching to three-year vaccine protocls, they are doing so with whatever vaccine they happen to be using. So if you want to switch to the three-year protocol, at least there is one vaccine that distinquishes itself because it had been challenged at three years.
Everman: It practitioners want to assess immunity, they can monitor the immue response by checking serum antibody titers for canine distemper and parvovirus. As mentioned earlier I regard IgG levels of 1:100 or greater as reflections of protection for caine distemper virus or parvovirus.
Faunt: At some point, we have to move to the three-year protocol because we won't have evidence on population immunity until we do. We won't find out anything about herd immunity until the herd immunity is challenged.
Novak: But we do have a challenge study--a key piece of information many people have been waiting for....
Lewis: So there is general agreement that, as a challenge study, it certainly shows efficacy against these three antigens for a three-year duration?
Novak: Yes.
Glickman: Do we know if these animals shed any of the challenge organisms? Are they contagious even though they are not clinically ill? I just don't want practitioners to get the idea that because 100% of a relatively small number of dogs were protected in this challenge study, that 100% of all vaccinated dogs in practice will be solidly protected.
Novak: [To learn that] it makes sense to use the vaccine on a large scale, such as in a field test.
Lewis: Banfield has taken the position for quite some time that we need evidence to support a change in our vaccination strategy....That is why we are conducting a clincial field trial involving 1,000 dogs. Between the Ft. Dodge study and our study, we feel we can make an informed decision about whether or not to use this vaccine....In addition to following the dogs fiven the three-year vaccine, we'll administer the current one-year vaccine to a cohort group matched for breed, age, gender, and hospital location. And we have historical data on adverse reactions for comparision purposes. Our primary interest is comparing the new vaccine with our current vaccine...We think this vaccine is an important development in preventative medicine. If the field trial results indicate that short-term effects are sililar to our current distemper combination vaccines, we will adopt the vaccine for general use in our practice.....
PREVENTATIVE CARE PROGRAMS:
Faunt: It's an exciting opportunity for us to rethink our preventative-care programs. The every 6-month physical is very important, along with other preventative care procedures, such as heart-worm preventation, flea & tick prevention, vaccination, and fecal examination and deworming. This is an opportunity to do an even better job of preventative care.
Engler: We can go from being vaccination-driven to examination-driven. It's wellness diagnostics and early prevention.....
Novak: Rabies vaccination is administered every three years, so this is just another set of antigens that can be given every three years......
Levy: Some of our concerns about shifting to the three-year protocol include difficulty getting dogs in for visits, decreased income, and shitfing doctor and team time to other purposes. How do you address these concerns and how will you stagger your vaccines?
Lewis: We have a preventative-care program, and vaccinations are only one part of it.
Novak: From a client's perspective, the many components of a preventative-care program can be confusing. We need to make it simple, but owners also want their pets to be healthy and protected. Our wellness plans provide all the services necessary for optimum health........
Levy: Your model is a wellness-based model with a preventative-care package. How do you address the veterinarian who has based his or her practice on vaccination visits with vaccination paying for the spays and everythin else he or she gives away?
Novak: Look at the dental community. There was a time when cavities were the driver, and now the real driver is regular exams and cleaning. Advocating twice-a-year physical exams trying to detect disease early; and emphasizing wellness, client education, and the value of the visit are what we need to move to in the veterinary profession.....
Faunt: Part of my job is to take phone calls from our doctors who have questions about care. The most frequent question is about abnormal preoperative blood work in an apparently healthy patient presented for a dental cleaning. I don't think a week goes by we don't hear about an important problem detected in an apparently healthy pet through a wellness check-up........
Lewis: This is exciting--that we can tailor a wellness program to certain breeds and situations. Excitment is also building about gene markers for different diseases. In the future, we will be able to test for those particular genes and tailoring the preventative-care program to that particular breed or family....
Glickman: .........high-risk giant breeds should receive special yearly examinations [for osteosarcoma], even if it's just palpation of the long bones or radiography. I think you need to design wellness programs that are tailor-made for specific breeds and individuals.
Lewis: We are on the cusp of a huge change in veterinary medicine, and that is evidence based medicine...
Novak: It's interesting that preventive care for pets hasn't been a dominant focus of our profession, particularly in veterinary education....Early disease identication means there's a better chance for effective treatment....
Lewis: I agree. The same thing is starting to occur in pet practice. In our veterinary schools, we tend to focus on the reactive side of medicine, on the healing of disease problems. In pet practice, we are moving toward preventive medicine, as well as more sophisticated medical and surgical services. It is an exciting time....
Novak: This is an exciting time in veterinary medicine. Initiation of news vaccine protocols is a small change, but one that can lead to many positive changes in terms of refocusing veterinary medicine on the bigger picture of healthcare.
PUBLISHED AS PART OF VETERINARY MEDICINE. A roundtable discussion sponsored by an unrestricted grant from Fort Dodge Animal Health. Copyright 2004. All rights reserved. Published by Advanstar Veterinary Healthcare Communications, Lenexa, KS. Printed in the USA. Produced as a part of the VETERINARY MEDICINE journal. For full text, request a copy from this journal.