Pet Overvaccination Increases Risk of Adverse Events

Did you ever wonder about the dose and frequency of vaccines recommended for your pet? Can overvaccination occur and are there attendant risks? Perhaps you are unaware that vaccines are not just made up of the intended vaccine antigen(s) but also contain a long list of other excipient materials:

• Adjuvants like aluminum salts and squalene to enhance the immune response (for killed inactivated vaccines).
• Preservatives added to prevent bacterial or other contamination (thimerosal = mercury salts).
• Stabilizers to keep the vaccine potent during transportation and storage (sugars or gelatin).
• Residual trace materials used during the manufacturing process and removed. These include: cell culture materials, used to grow the vaccine antigens (fetal calf serum, egg protein, culture media); inactivating ingredients, used to kill viruses or inactivate toxins (formaldehyde); antibiotics, used to prevent contamination by bacteria (neomycin, gentamicin).

Given this background, it is easy to imagine the potential adverse effects of overvaccination.BUT, even today only about 40% of veterinarians are estimated to follow the current WSAVA, AVMA, AAHA and BVA vaccine policy guidelines. Further, there is no such thing as an ‘up to date’ or ‘due’ vaccination. Enlightened veterinarians now can offer separated vaccine components, rather than give them all together, since the published data show more adverse reactions when multiple vaccines are administered together.Killed, inactivated vaccines containing adjuvants make up about 15% of veterinary biologicals used, but have been associated with 85% of the post-vaccination reactions. While adjuvants have been used safely in human and veterinary medicine for decades, but there is increasing worldwide concern about the safety of using thimerosal (mercury) and aluminumHow and Why do Adverse Events, called Vaccinosis, Occur?

• Millions of people, pets and livestock vaccinated annually.
• Reactions are relatively rare — about 3-5 events per 100 vaccines given.
• Affects those genetically predisposed.
• Can be acute, sub-acute, and delayed for 30-45 days.
• New data links reactions to integrity and function of gut microbiome.
• Heavy metal exposure from vaccines is an emerging concern for humans, pets and livestock. Aluminum and mercury found in brains of autistic people, and from vaccine adjuvants that cross the blood –brain barrier after injection, and then persist life-long.

Vaccines containing aluminum are commonly used in sheep herd management and have been found to cause the ASIA syndrome (Autoimmune Inflammatory Syndrome Induced by Adjuvants). Studies from Spain evaluated sheep divided into 3 groups: control, aluminum adjuvant only and aluminum adjuvanted vaccine.:16 inoculations were given to the groups over an 11-month period. Results showed behavioral changes, aggression, stereotypic and excitatory responses, compulsive eating, and reduced sociability in both the adjuvant alone and adjuvanted vaccine groups but not in the controls. Changes were more pronounced in the vaccinated group; and some began after only 7 inoculations.What About Vaccine Dosage in Relation to Age & Size?

Neonates & Infant Children

• Urgent need to remove heavy metals, like aluminum and mercury, from infant vaccines.
• Currently, neonates receive 17 times more aluminum from vaccines than allowed if doses were adjusted for body weight.
• Body weight is ignored in human vaccines, as they use these heavy metals to enhance immune efficacy.
• Experts now urge that aluminum and mercury not be given in vaccines until after brain maturation (6-7 months of age but preferably 12 months).
• Alternatives being considered are calcium phosphate and zinc.

Small Breed Dogs

• Small breed adult dogs, between 3-9 years of age, were studied.
• Dogs were healthy and had no vaccines for at least 3 years.
• Purpose was to determine if just half-dose of bivalent CDV and CPV vaccine elicited protective serum antibody titer responses.
• Titer levels compared 1- and 6-months later vs pre-vaccine titers.
• Half-dose vaccine resulted in sustained protective serum antibody titers for all dogs studied.

Vaccination May Not Equate to Immunization But, vaccinated and truly immunized animals should be fully protected from disease. Immune memory cell immunity should persist life-long.Giving boosters to immunized animals is unwise, as it will introduce unnecessary antigen, excipient adjuvants, preservatives and the other materials described above.What is Sterilizing Immunity?

• An immune response that completely prevents and eliminates an infection.
• Animals properly immunized against the clinically important viral diseases have sterilizing immunity that not only prevents clinical disease but also prevents infection. Only the presence of antibody can prevent infection.
• An animal with a positive serum antibody test is protected from infection.
• Vaccinating that animal would not cause a significant increase in antibody titer, but hypersensitivity to vaccine components (e.g. fetal bovine serum) may develop.
• Furthermore, the animal doesn’t need to be revaccinated and should not be revaccinated since the vaccine could cause an adverse reaction (hypersensitivity disorder).
• But, not all vaccines produce sterilizing immunity
• Those that do include: distemper virus, adenovirus, and parvovirus in the dog, and panleukopenia virus in the cat.
• Examples of vaccines that produce non-sterile immunity would be leptospirosis, bordetella, canine influenza, rabies virus, and herpesvirus and calicivirus — the upper respiratory viruses of cats.
• While non-sterile immunity may not protect the animal from infection, it should keep the infection from progressing to severe clinical disease.

The bottom line here is to avoid overvaccination and, whenever possible, measure serum antibody titers instead.

References

• J Am Hol Vet Med Assoc.  41; 12-21, winter 2015.
• Ivanovski et al. J Trace Elements in Med and Biol.  51:138-140, 2019.
• Pinczowski, et al. Pharm Res, Nov 3, 2018; org/10/10.1016/ j. phrs.2018.10.019
• Weiler & Ricketson. J Trace Elements in Med and Biol. 48: 67-73, 2018.