- Email: [email protected]
Concluding remarks
Veterinary Microbiology 117 (2006) 98–101 www.elsevier.com/locate/vetmic
Concluding remarks Marian C. Horzinek * Haydnlaan 15, 3723KE Bilthoven, The Netherlands
The articles in this issue have emphasized vital elements in pet vaccination: from the necessity to maintain – or rather increase – the level of herd immunity in the dog and cat populations to the nonsensical routine of yearly boosters against parvo-, adeno- and morbillivirus infections. The conclusions can be encapsulated in the statement: we vaccinate the same animals too often, but too few animals in a population. This statement needs a modifier: there are vaccines that require frequent boosters, some more often than yearly, but this is not true for the core vaccines. It is important to distinguish between an injection (with the intention to immunize), an immunization (with the objective to induce specific antibodies and Tcells) and a vaccination (with the intention to protect against a pathogen, i.e. to result in long-term memory cell populations with the propensity to rapidly divide upon infection). Not every injection immunizes, not every immunization protects. Also, ‘‘immunization’’ is not synonymous with vaccination—a dog can be immunized against any antigenic protein, e.g. bovine serum albumin. Vaccination is an immunization with the objective to protect against diseases and conditions—again not necessarily against infections. It is possible to vaccinate, e.g. against fertility, nicotine and cancer. * Tel.: +31 30 2287029; fax: +31 30 2252857. E-mail address: [email protected].
Vaccine protection of a household pet could only be evidenced by an infection experiment, which is out of the question, of course. Challenge infections of vaccinated laboratory dogs, however, have been used to establish the 3-years duration of immunity discussed in this symposium, which should rather be called ‘‘duration of protection’’. Challenge infections, e.g. using canine parvovirus, would typically employ 100,000 tissue culture infectious doses/ml—but even here some critical comments are in place: Is this overkill? How does a culture infectious dose relate to a dog infectious dose? What is the minimum infectious dose to make an immunologically naı¨ve animal sick? What is the level of parvovirus excretion by a sick animal, and what would constitute a realistic ‘‘field’’ dog infectious dose? This pile-up of assumptions left everybody dissatisfied and has led to a different approach to assess the degree (and duration) of immunity: serology. Although recognized as being only one arm of the immune response, ‘‘correlates of protection’’ have been established, and after, e.g. parvovirus vaccination, protection would be assumed at an antibody titer of 80 in a haemagglutination inhibition reaction. In decisions whether or not to revaccinate an adult animal, however, evidence of antibody presence would suffice to indicate immunological memory and to discourage the yearly shot. Titer values are prone to misinterpretation, laboratory-dependent variation and have done more
0378-1135/$ – see front matter # 2006 Elsevier B.V. All rights reserved. doi:10.1016/j.vetmic.2006.04.015
M.C. Horzinek / Veterinary Microbiology 117 (2006) 98–101
harm than good in veterinary practice—see feline infectious peritonitis.
99
nobody’s interest, and a concerted action of the profession, academia and industry is required to break this stalemate.
1. The professional ‘code of practice’ In view of the uncertainties amongst practicing vets, the professional organisations would be well advised to regularly update a ‘code of vaccination practice’ (rather than issuing ‘vaccination schedules’ or ‘schemes’) that defines the standard of care. The code is the result of a self-governing process that takes professional, societal, emotional, managerial, financial, etc., arguments into account. Scientific consensus is an element, and should be the most important one, but historically has never been, largely due to a wellintended conservatism. The standard of care is about ‘‘defining’’, not about ‘‘recognizing’’, and the definitions have legal ramifications. When addressing the inertia, it is interesting to note that in the United States ‘‘. . . conformity to custom is not in itself an exercise of care as a matter of law’’ (30 AmJur2nd Evidence §1123). In the past, by adhering to label instructions, vets could shift litigation to the vaccine manufacturer. But in 1996, the US Supreme Court refused review of the Lynbrook Farms versus SmithKline Beecham Corp. (117 S.Ct.178) case, declaring that only USDA requirements of safety, efficacy, potency and purity must be met by the manufacturer. As a consequence, future consumer claims will increasingly be centered at the practitioner: malpractice, failure to adhere to the standard of care, wrong vaccine selection and administration, and no informed consent by the client may all result in litigation, in the USA—but this is not true for other countries. A recent monograph on vaccination practices in Germany states ‘‘Die Gebrauchsinformation ist der bindende Rahmen fu¨r die Anwendung jedes Mittels’’ (the package insert is the stringent framework for the application of any product; Selbitz and Moos, 2003). While this legislation offers a protection advantage for colleagues in Germany, it patronizes an academic profession. A science-based code of practice could be at variance with industry interests, and progress is curtailed. This is in
2. What do companion animal practitioners think? At the Prague meeting, a Intervote1 Electronic Voting and Response System was used to poll the audience. Using wireless voting pads with colour coded buttons, the delegates could key in their answers to questions projected onto video screens in the lecture hall. Table 1 gives the results. Interpretation of the data may differ according to the reader’s preference, but some salient details can be recognized. The poll does not represent a balanced practitioners’ view, when less than 1/4 of the respondents work in practice (question 4). More than 80% of the participants work in multi-vet companion animal practices or faculty clinics (question 5), and their degree of information exchange and sophistication may not be representative for the profession at large. When comparing puppy and kitten vaccinations, the latter seem to be underprivileged in numbers (questions 6 and 8) and revaccinations (questions 7 and 9). The highest abstention rates are seen when it comes to diagnosing parvovirosis or distemper (questions 10 and 11), which may be a reflection of the prevalence of non-clinicians in the audience (about one-half—question 5); both diseases are diagnosed in vaccinated animals, however. If single component vaccines were available, an impressive 83% would use them in addition to ‘‘booster vaccines’’ (question 14). For a move to a new vaccination scheme based on 3-years DOI, more than 2/3 of the respondents would want to see independent data (question 15), while 11% could not care less (‘‘nice face of the sales rep’’) about an argument, but would follow anyway. These remarks are intended only as ‘food for thought’ and by no means represent a statistically valid assessment of opinion. To arrive at the code of practice, however, data of this sort are important, and need to be collected professionally.
100
M.C. Horzinek / Veterinary Microbiology 117 (2006) 98–101 Table 1 (Continued )
Appendix A Table 1 1. Are you A veterinarian Not a veterinarian
90% 10%
n = 130 2. Did you graduate in 2001–2005 1996–2000 1991–1995 1986–1990 1981–1985 1976–1980 1971–1975 1966–1970 1960–1965 Before 1960
4% 14% 17% 16% 22% 16% 5% 5% 1% 0%
n = 128 3. Are you Female Male
35% 65%
n = 128 4. You are currently (indicate only one/main activity) In practice At a faculty In research In industry A journalist Other
23% 32% 8% 29% 2% 5%
n = 130 5. Please answer this question only if you are in a practice You practice in Mixed practice, single vet Mixed practice multiple vets Small animal only practice single Small animal only practice multiple vet Faculty clinic Others
2% 8% 8% 42% 40% 2%
n = 53 6. What percentage of puppies out of the total population in your country gets a full puppy vaccination? 0–25% 16% 26–50% 24% 51–75% 37% 76–100% 23% n = 100 7. What percentage of puppies in your country that receives a primary vaccination will return for subsequent boosters (2 years of age and more)?
0–25% 26–50% 51–75% 76–100%
9% 40% 35% 17%
n = 101 8. What percentage of kittens out of the total population in your country gets a full kitten vaccination? 0–25% 45% 26–50% 41% 51–75% 13% 76–100% 1% n = 102 9. What percentage of kittens in your country that get a primary vaccination will return for subsequent boosters (2 years of age and more)? 0–25% 36% 26–50% 43% 51–75% 18% 76–100% 4% n = 101 10. Do you see vaccinated dogs going down with signs of what you think is parvovirosis? Yes 37% No 38% Abstention 25% n = 89 11. Do you see vaccinated dogs going down with signs of what you think is distemper? Yes 26% No 58% Abstention 16% n = 96 12. Are you aware of the recent 3-years duration of immunity (DOI) launch by companies for the CPV, CDV and CAV components of their canine vaccine range? Yes 79% No 16% Abstention 5% n = 105 13. Would you consider a move to a new vaccination scheme, based on 3-year DOI, for some components and single component vaccines as helpful to your practice? Yes 59% No 25% Abstention 16% n = 101 14. If single component vaccines were available, would you use them in addition to ‘‘booster vaccines’’?
M.C. Horzinek / Veterinary Microbiology 117 (2006) 98–101 Table 1 (Continued ) Yes No Abstention
83% 5% 12%
n = 100 15. Which argument (choose one only) would convince you to adopt the earlier mentioned change? Loyalty to company 0% Price 2% Technical information from a company 12% Pet owner awareness of DOI 8% Independent scientific information 65% Trust in company 1% Service of a company 1% Nice face of the sales rep 11% n = 101 16a. If a mucosal (intranasal, oral) vaccine was an available native to an injectable one, would you use it in dogs? Yes No Abstention
alter52% 36% 12%
n = 99 16b. If a mucosal (intranasal, oral) vaccine was an available native to an injectable one, would you use it in cats? Yes No Abstention n = 104
alter44% 44% 12%
101
Concluding remarks Marian C. Horzinek * Haydnlaan 15, 3723KE Bilthoven, The Netherlands
The articles in this issue have emphasized vital elements in pet vaccination: from the necessity to maintain – or rather increase – the level of herd immunity in the dog and cat populations to the nonsensical routine of yearly boosters against parvo-, adeno- and morbillivirus infections. The conclusions can be encapsulated in the statement: we vaccinate the same animals too often, but too few animals in a population. This statement needs a modifier: there are vaccines that require frequent boosters, some more often than yearly, but this is not true for the core vaccines. It is important to distinguish between an injection (with the intention to immunize), an immunization (with the objective to induce specific antibodies and Tcells) and a vaccination (with the intention to protect against a pathogen, i.e. to result in long-term memory cell populations with the propensity to rapidly divide upon infection). Not every injection immunizes, not every immunization protects. Also, ‘‘immunization’’ is not synonymous with vaccination—a dog can be immunized against any antigenic protein, e.g. bovine serum albumin. Vaccination is an immunization with the objective to protect against diseases and conditions—again not necessarily against infections. It is possible to vaccinate, e.g. against fertility, nicotine and cancer. * Tel.: +31 30 2287029; fax: +31 30 2252857. E-mail address: [email protected].
Vaccine protection of a household pet could only be evidenced by an infection experiment, which is out of the question, of course. Challenge infections of vaccinated laboratory dogs, however, have been used to establish the 3-years duration of immunity discussed in this symposium, which should rather be called ‘‘duration of protection’’. Challenge infections, e.g. using canine parvovirus, would typically employ 100,000 tissue culture infectious doses/ml—but even here some critical comments are in place: Is this overkill? How does a culture infectious dose relate to a dog infectious dose? What is the minimum infectious dose to make an immunologically naı¨ve animal sick? What is the level of parvovirus excretion by a sick animal, and what would constitute a realistic ‘‘field’’ dog infectious dose? This pile-up of assumptions left everybody dissatisfied and has led to a different approach to assess the degree (and duration) of immunity: serology. Although recognized as being only one arm of the immune response, ‘‘correlates of protection’’ have been established, and after, e.g. parvovirus vaccination, protection would be assumed at an antibody titer of 80 in a haemagglutination inhibition reaction. In decisions whether or not to revaccinate an adult animal, however, evidence of antibody presence would suffice to indicate immunological memory and to discourage the yearly shot. Titer values are prone to misinterpretation, laboratory-dependent variation and have done more
0378-1135/$ – see front matter # 2006 Elsevier B.V. All rights reserved. doi:10.1016/j.vetmic.2006.04.015
M.C. Horzinek / Veterinary Microbiology 117 (2006) 98–101
harm than good in veterinary practice—see feline infectious peritonitis.
99
nobody’s interest, and a concerted action of the profession, academia and industry is required to break this stalemate.
1. The professional ‘code of practice’ In view of the uncertainties amongst practicing vets, the professional organisations would be well advised to regularly update a ‘code of vaccination practice’ (rather than issuing ‘vaccination schedules’ or ‘schemes’) that defines the standard of care. The code is the result of a self-governing process that takes professional, societal, emotional, managerial, financial, etc., arguments into account. Scientific consensus is an element, and should be the most important one, but historically has never been, largely due to a wellintended conservatism. The standard of care is about ‘‘defining’’, not about ‘‘recognizing’’, and the definitions have legal ramifications. When addressing the inertia, it is interesting to note that in the United States ‘‘. . . conformity to custom is not in itself an exercise of care as a matter of law’’ (30 AmJur2nd Evidence §1123). In the past, by adhering to label instructions, vets could shift litigation to the vaccine manufacturer. But in 1996, the US Supreme Court refused review of the Lynbrook Farms versus SmithKline Beecham Corp. (117 S.Ct.178) case, declaring that only USDA requirements of safety, efficacy, potency and purity must be met by the manufacturer. As a consequence, future consumer claims will increasingly be centered at the practitioner: malpractice, failure to adhere to the standard of care, wrong vaccine selection and administration, and no informed consent by the client may all result in litigation, in the USA—but this is not true for other countries. A recent monograph on vaccination practices in Germany states ‘‘Die Gebrauchsinformation ist der bindende Rahmen fu¨r die Anwendung jedes Mittels’’ (the package insert is the stringent framework for the application of any product; Selbitz and Moos, 2003). While this legislation offers a protection advantage for colleagues in Germany, it patronizes an academic profession. A science-based code of practice could be at variance with industry interests, and progress is curtailed. This is in
2. What do companion animal practitioners think? At the Prague meeting, a Intervote1 Electronic Voting and Response System was used to poll the audience. Using wireless voting pads with colour coded buttons, the delegates could key in their answers to questions projected onto video screens in the lecture hall. Table 1 gives the results. Interpretation of the data may differ according to the reader’s preference, but some salient details can be recognized. The poll does not represent a balanced practitioners’ view, when less than 1/4 of the respondents work in practice (question 4). More than 80% of the participants work in multi-vet companion animal practices or faculty clinics (question 5), and their degree of information exchange and sophistication may not be representative for the profession at large. When comparing puppy and kitten vaccinations, the latter seem to be underprivileged in numbers (questions 6 and 8) and revaccinations (questions 7 and 9). The highest abstention rates are seen when it comes to diagnosing parvovirosis or distemper (questions 10 and 11), which may be a reflection of the prevalence of non-clinicians in the audience (about one-half—question 5); both diseases are diagnosed in vaccinated animals, however. If single component vaccines were available, an impressive 83% would use them in addition to ‘‘booster vaccines’’ (question 14). For a move to a new vaccination scheme based on 3-years DOI, more than 2/3 of the respondents would want to see independent data (question 15), while 11% could not care less (‘‘nice face of the sales rep’’) about an argument, but would follow anyway. These remarks are intended only as ‘food for thought’ and by no means represent a statistically valid assessment of opinion. To arrive at the code of practice, however, data of this sort are important, and need to be collected professionally.
100
M.C. Horzinek / Veterinary Microbiology 117 (2006) 98–101 Table 1 (Continued )
Appendix A Table 1 1. Are you A veterinarian Not a veterinarian
90% 10%
n = 130 2. Did you graduate in 2001–2005 1996–2000 1991–1995 1986–1990 1981–1985 1976–1980 1971–1975 1966–1970 1960–1965 Before 1960
4% 14% 17% 16% 22% 16% 5% 5% 1% 0%
n = 128 3. Are you Female Male
35% 65%
n = 128 4. You are currently (indicate only one/main activity) In practice At a faculty In research In industry A journalist Other
23% 32% 8% 29% 2% 5%
n = 130 5. Please answer this question only if you are in a practice You practice in Mixed practice, single vet Mixed practice multiple vets Small animal only practice single Small animal only practice multiple vet Faculty clinic Others
2% 8% 8% 42% 40% 2%
n = 53 6. What percentage of puppies out of the total population in your country gets a full puppy vaccination? 0–25% 16% 26–50% 24% 51–75% 37% 76–100% 23% n = 100 7. What percentage of puppies in your country that receives a primary vaccination will return for subsequent boosters (2 years of age and more)?
0–25% 26–50% 51–75% 76–100%
9% 40% 35% 17%
n = 101 8. What percentage of kittens out of the total population in your country gets a full kitten vaccination? 0–25% 45% 26–50% 41% 51–75% 13% 76–100% 1% n = 102 9. What percentage of kittens in your country that get a primary vaccination will return for subsequent boosters (2 years of age and more)? 0–25% 36% 26–50% 43% 51–75% 18% 76–100% 4% n = 101 10. Do you see vaccinated dogs going down with signs of what you think is parvovirosis? Yes 37% No 38% Abstention 25% n = 89 11. Do you see vaccinated dogs going down with signs of what you think is distemper? Yes 26% No 58% Abstention 16% n = 96 12. Are you aware of the recent 3-years duration of immunity (DOI) launch by companies for the CPV, CDV and CAV components of their canine vaccine range? Yes 79% No 16% Abstention 5% n = 105 13. Would you consider a move to a new vaccination scheme, based on 3-year DOI, for some components and single component vaccines as helpful to your practice? Yes 59% No 25% Abstention 16% n = 101 14. If single component vaccines were available, would you use them in addition to ‘‘booster vaccines’’?
M.C. Horzinek / Veterinary Microbiology 117 (2006) 98–101 Table 1 (Continued ) Yes No Abstention
83% 5% 12%
n = 100 15. Which argument (choose one only) would convince you to adopt the earlier mentioned change? Loyalty to company 0% Price 2% Technical information from a company 12% Pet owner awareness of DOI 8% Independent scientific information 65% Trust in company 1% Service of a company 1% Nice face of the sales rep 11% n = 101 16a. If a mucosal (intranasal, oral) vaccine was an available native to an injectable one, would you use it in dogs? Yes No Abstention
alter52% 36% 12%
n = 99 16b. If a mucosal (intranasal, oral) vaccine was an available native to an injectable one, would you use it in cats? Yes No Abstention n = 104
alter44% 44% 12%
101