Vaccines and vaccination: Issues and controversies (Part 2) (Proceedings)
A. Vaccine Selection
Today, the list of licensed vaccines for just the dog and cat is large and diverse ...approximately 110 canine vaccines and 70 feline vaccines are available. Considerable differences among vaccines for the same antigen exist. The following FAQs center on scientific issues that should be considered when selecting vaccines for individual patients.
1. Should Modified-Live vaccines be selected over Killed vaccines?
When the option is available-yes. This is particularly true for cats.
Killed (inactivated) vaccines
NOTE: for some diseases, eg, leptospirosis, canine influenza, FIV, canine rabies, the only current option available is a Killed vaccine.
NOTE: Indications for the use of a Killed vaccine include: 1) vaccination of the pregnant patient (although one has to ask..."why is it necessary to vaccinate a pregnant dog or cat?") ...and 2) it is recommended that an immune compromised cat (e.g. FeLV and/or FIV positive) should only be vaccinated with a Killed vaccine. One could apply this rationale to all immune suppressed patients or patients regardless of the cause (e.g. chemotherapy). However...there are no scientific studies supporting this recommendation.
Modified-Live (attenuated) vaccines
4. How does a Recombinant Vaccine compare to killed and modified-live vaccine?
Recombinant vaccines (and there are different kinds of recombinant vaccines) are the latest in vaccine technology used in humans and animals. In veterinary medicine, they are widely used throughout the US, Canada, Europe and the UK.
Recombinant vectored vaccines
5. Are there vaccines I should NOT select for use?
Yes-although the AAFP and the AAHA Vaccine Guidelines have categorized vaccines that are "not generally recommended" or "not recommended" (respectively), note that these are licensed vaccines; they are legal to administer in the US. Of all the vaccines categorized as "not recommended". Feline Infectious Peritonitis (FIP) and Canine Coronavirus vaccines are included because of the limited data available to demonstrate efficacy in a clinical setting.
Killed parvovirus and Giardia spp. vaccine were not recommended...these vaccines are discontinued.
When feasible, veterinarians should avoid adjuvanted vaccine in cats (all killed feline vaccines are adjuvanted) as a reasonable and recommended means of mitigating risk of vaccine-associated sarcoma (VAS).
6. Should I select 'combination' (ie, multivalent) products for my patients?
Immunologists will point out that the immune system of a healthy dog or cat is quite capable of responding to all of the combination antigens in vaccines on the market today. 3-in-1 and 4-in1 products are commonly used...but even 5-in-1 and 6-in-1 products are considered to be efficacious.
IMPORTANT: DO NOT MIX vaccines that are not specifically indicated by the manufacturer to be mixed.
7. When selecting vaccines for "kennel cough", which is recommended: Intranasal (IN) or Parenteral (SubQ)?
The IN (bi-valent) vaccine containing Bordetella bronchiseptica and parainfluenza virus is preferred over the parenteral (SubQ) B. bronchiseptica vaccine for the following reasons:
B. Administration of Vaccine
The following FAQs address issues that pertain to vaccine administration and developing a protocol applicable to the patient population at risk.
Puppy and Kitten shots (i.e., the 'initial vaccine series')...what are the minimum and maximum intervals between doses?
Most authors agree...avoid minimum intervals of less than 2 weeks.1 Reason: vaccine-induced interference...the first dose could interfere with the 2nd dose if given, say, 1 week later. NOTE: this is NOT antibody interference and, as such, is NOT antigen specific...eg, a D-A2-P given this week and a Rabies given next week might result in failure of the Rabies vaccine to immunize.
In a puppy or kitten, what's the reasonable time (days-months) between vaccination and onset-of-immunity?
IMPORTANT: When should the last dose of vaccine, in the initial series, be given?
For both the dog and cat, all Guidelines (AAHA, AAFP, and WSAVA) recommend 14-16 weeks of age. The rationale behind these recommendations is to insure that interfering levels of maternal antibody are not circulating at the time the last dose in the initial vaccine series is administered. Several manufacturers now list earlier completion times (eg, 12 and 13 weeks in the US; 10 weeks in the UK and Europe). Such practice is NOT recommended.
How many doses of vaccine should be given to a dog or cat presented for their initial vaccine series if the patient is older than 15-16 weeks of age?
Most veterinarians recommend administering 2 doses, 3 to 4 weeks apart.
Can I reduce the volume (e.g. from 1 mL to 0.5 mL) of vaccine when inoculating a toy breed dog?
No-doing so may leave the toy breed (small dog) susceptible for one or more of the diseases you're trying to prevent. In the case of RABIES, reducing the volume is equivalent to NOT IMMUNIZING the patient. In some locations, doing so could represent medical malpractice or a breach in the Standard of Care. ("Small Breed" dogs are generally considered to be those that weigh less than 20 pounds of weight as adults)
Can I mix vaccines from different manufacturers?
No-NEVER do this in the same syringe! On the other hand, vaccines from different manufacturers may be administered at different sites in the same patient at the same visit.
Once reconstituted, how long can a Modified-live vaccine dose be stored at room temperature and still be safe/effective?
It varies-canine distemper and feline herpesvirus-1 vaccine can lose immunizing capability within 2-3 hours. Parvovirus vaccines (canine and feline panleukopenia), on the other hand may be stable for a few days. RECOMMENDATION: For all MLV vaccines...reconstitute and use within 1 hour. If not used within 2 hours...discard the product.
Can I give a parenteral vaccine dose and, at the same visit, give an intranasal vaccine dose for the same disease(s)?
Yes...this is done routinely. For example, administering a parenteral D-A2-P-P (distemper-adeno-2-parvovirus-parainfluenza) plus an intranasal "kennel cough" vaccine (which usually contains Bordetella + parainfluenza virus) inoculates the patient with 2 doses of parainfluenza virus. While it might seem that the patient would derive a superior immune response consisting of both a circulating humoral immune response (IgG) + a local immune response from the intranasal vaccine (secretory IgA), there is minimal evidence that doing this might be beneficial in an individual dog.
Can a vaccine intended for intranasal administration be effectively given parenterally, for example, SQ administration of an intranasal B. bronchiseptica + parainfluenza?
NO! This MUST NOT be done. Severe post-vaccination complications associated with replication of bacteria and release of toxic proteins that target the liver could cause acute hepatocellular injury and death following a single dose. WARNING: some products licensed for IN administration are packaged as though they are intended for parenteral administration. ALL PERSONNEL AUTHORIZED TO ADMINISTER VACCINE MUST BE TRAINED ON PROPER ADMINISTRATION TECHNIQUES.
Can a vaccine licensed for intranasal administration be effectively administered orally to a patient that resists intranasal administration?
No-administering these vaccines by the oral route results in rapid inactivation of the vaccine without immunization.
Are antibody titers a valid assessment of immunity?
Depends! ...specific limitations apply to titers when assessing the immune status of an individual patient. First, titers for CDV, CPV, and feline parvovirus (panleukopenia) correlate extremely well with immunity...dogs/cats that have a "positive" titer are considered immune. Second, a "negative" titer does not always correlate with susceptibility. Antibody is a glycoprotein and does dissipate over time. However, immunologic "memory" (B-lymphocytes) is retained for many years for these 3 diseases. Exposure to virulent virus in a previously vaccinated, antibody negative patient typically results in a rapid anamnestic 'boost' of antibody titer and a protective immune response. Annual or triennial boosters are merely a form of immunologic insurance for these 3 diseases. Most animals don't need it.
For other diseases, antibody titers are not good correlates of protective immunity. Feline herpesvirus-1 and feline calicivirus titers can be obtained, but are not recommended for the assessment of the individual patient's immunity to those diseases. FeLV titers are not valid at all because of the lack of a valid test method. Leptospirosis titers are routinely performed but generally are used to define exposure/infection...not immunity. See RABIES TITERS (next question).
Can rabies titers be used to assess immunity in a dog or cat subsequent to vaccination?
No. States/local municipalities generally do not accept FAVN (fluorescent antibody virus neutralization) rabies titer results as a replacement for vaccination or as means of assessing immunity in a dog/cat that has been involved in a bite incident. FAVN test results (only provided in the US by Kansas State University and DoD [military members only]) are used to comply with requirements on the exportation of animals to designated Rabies-Free areas.
COST: $47 (2009 price); takes 2-3 weeks.
Attn: FAVN Rabies Laboratory
When would an antibody titer be indicated in an individual patient?
If an adult dog/cat has exceeded the recommended booster interval by several months is it necessary to administer 2 doses of vaccine, 3 to 4 weeks apart, before considering the patient "immunized"?
No. A single booster dose (MLV vaccine being preferred), is likely to be sufficient assuming the patient was vaccinated at some point earlier in life..up to 3 years. Immunologic "memory" is the reason.
Overdue for RABIES: In the event a dog or cat has exceeded the vaccination interval required by State or local statutes for RABIES, a single dose is still all that is required to 'boost' the patient...immunologically speaking. Legally speaking, however, it's always wise to check the official position of your State by contacting the State Dept of Public Health or the State Public Health Veterinarian.
C. Core Vaccines
Are Dobermans and Rottweilers still unlikely to respond to Parvovirus vaccination?
Today, most agree that these breeds do NOT have a uniquely higher risk of acquiring parvovirus following exposure nor are they more likely than any other breed to fail to be immunized following vaccination. The high disease incidence and the frequency of vaccine failures recognized in the late 70's and early 80's is no longer an issue in the US.
Does the new "strain" of canine parvovirus (CPV- 2c) warrant the use of a new vaccine or a specific vaccine brand already on the market?
No. First, CPV-2c is not a new 'strain'...it's a biological variant of parvovirus that has emerged as part of the normal 'genetic drift' of the virus. The changes in the virus are limited to a small number of nucleotide base-pairs. CPV-2b is still most prevalent in the US, but CPV-2c is being reported. It's actually been around 10 years since it was first reported in Europe.
Consider the following FACTs:
In other words...the emergence of CPV-2c in the US poses NO need to change either vaccines or vaccination schedules.
Is there any advantage to using the recombinant canine distemper virus (rCDV) vaccine over conventional MLV vaccines? (There are NO killed distemper vaccines)
Yes-particularly in young dogs and dogs considered to be at risk of exposure to CDV.
In adult dogs, rCDV and MLV act very much alike.
In puppies, there are some important differences:
Are Non-Adjuvanted Feline vaccines still recommended over Adjuvanted?
Yes-the AAFP Advisory Panel that authored the Feline Vaccine Guidelines (2006) has suggested veterinarians should avoid the use of inflammatory vaccines whenever possible...that statement was specifically intended to address adjuvant-induced inflammation.
Adjuvants, by their very nature, induce inflammation, typically...chronic inflammation lasting days to weeks. The cellular response associated with adjuvant-induced inflammation is still regarded by most oncologists and other academicians who work with vaccines to be responsible for the DNA injury (oxidative injury) associated with metaplasia in fibroblasts. In genetically pre-disposed cats (it appears), there is risk of neoplastic transformation of fibroblasts into fibrosarcoma (or other types of mesenchymal tumor) . BE PRACTICAL...avoid adjuvanted vaccines in cats!
D. Non-Core Vaccines
Although vaccination recommendations for CORE vaccine are widely accepted, decisions regarding administration of vaccines considered to be NON-CORE are generally associated with much more controversy. The following FAQs address many of these controversies.
Is an intranasal vaccine for Bordetella bronchiseptica better or worse than the injectable vaccine?
The studies are clear. Both vaccine types effectively mitigate the signs of infection. There are some differences that favor
use of the intranasal vaccine:
When is the parenteral (SQ) B. bronchiseptica vaccine indicated?
It's indicated when the patient will not tolerate IN administration...don't fight the patient.
Is there any new information pertaining to Leptospirosis vaccines?
By Fall of 2010, it is anticipated that ALL manufacturers will have a 4-way leptospirosis vaccine. Licensure of vaccines containing more that the current 4 serovars is NOT anticipated. While there are some differences in the manufacturing process of each vaccine, they are all killed bacterins. Interestinly...all of these vaccines are considered to effective in presenting clinical disease for 12 to 14 months). One product is not adjuvanted. There are no live or recombinant leptospirosis vaccines.
Do Lyme disease vaccines work?
Yes. The published data is clear on the fact that the commercial vaccines for Lyme disease do a relatively good job of protecting dogs...for about 12 months. Don't expect 100% of the patients vaccinated to become immunized. Two vaccine types are on the market: a killed, whole spirochete and a recombinant OspA (outer surface protein-A). All vaccines depend on the same antigen, OspA, to immunize. There is NO advantage in using a killed vaccine over the recombinant Lyme vaccine...the newest Lyme disease vaccine is a killed vaccines that provides additional antigens (OspC) and therefore claims added protection against Lyme disease. However, the value of OspC-expressing spirochetes in this vaccine has not been demonstrated in dogs. Killed, whole spirochete vaccines appear likely to cause more post-vaccinal reactions than the recombinant vaccine.
None of the vaccines used in the US today cause a False '+' test result on the IDEXX 3Dx or 4Dx test for Lyme borreliosis.
Vaccines should NOT be used as part of the treatment for Lyme disease!