Vaccines are an important component of preventive veterinary medicine, reducing the morbidity and mortality associated with infectious diseases. However, vaccines are generally administered to healthy individuals and improvements in immune status are not easily noticeable.
Owners may notice adverse events (AE) or unwanted side effects believed to be associated with vaccination, often contributing to reduced acceptance of that vaccine or vaccines in general. Effective vaccination programs can reduce the incidence of specific diseases in populations, further increasing the need or value of vaccination.
Vaccine-related AEs are often due to manifestations of immune stimulation. These responses may be excessive in immunologically predisposed individuals. for genetic or acquired reasons. Identification of genetically at-risk individuals has been advocated to potentially enable personalized rather than mass vaccination, but identification methods are currently lacking.
Los vaccine components that have been identified as possible triggering factors Hypersensitivity reactions include gelatin, egg protein, antibiotics and latex. Some dogs with immediate hypersensitivity reactions after vaccination have been shown to have increased IgE reactivity to fetal calf serum, a product used as a medium in cell cultures.
Cell culture media may include albumin and other proteins of bovine origin, that remain in canine vaccines. Manufacturing can try to reduce or even eliminate such proteins to improve vaccine safety, but the specific threshold concentrations that could raise the risk are unknown.
STUDY CONDUCTED ON MILLIONS OF DOGS
In order to evaluate patient and vaccine factors associated with adverse events, a study carried out in the USA has carried out research in a group of 4,654,187 dogs, evaluating adverse effects that occurred up to 3 days after vaccination.
Electronic medical records of dogs vaccinated between January 1, 2016 and December 31, 2020 were searched for diagnoses of possible AD. Patient risk factors (age, sex, race, and weight) and number and type of vaccinations were extracted from these records.
Possible adverse events associated with the vaccine were identified if, within 3 days after vaccination, a diagnosis of vaccine reaction, whether mild, moderate or severe, allergic reaction, hives, anaphylaxis, cardiac arrest or death, was recorded. . Likewise, due to predominantly low incidence rates (< 1%), AE rates are expressed per 10,000 vaccination visits.
Adverse events were recorded after 31,197 vaccinations (0.19% or 19.4/10,000 visits). Regarding the type of vaccines, adverse events occurred less frequently in any vaccination involving Bordetella or vaccines against the canine influenza virus. Vaccines against the Bordetella and canine influenza virus also had the lowest AD rates if they were administered as the only vaccination in a visit (16.0/10,000 visits and 15.1/10,000 visits, respectively). On the contrary, the Lyme vaccines and anger had the highest rates of AD (21.3/10,000 and 20.9/10,000 visits, respectively).
At this point, the researchers explain that “a proteomic analysis of canine vaccines recently found that Rabies vaccines had significantly more protein than other canine vaccines”, and this diversity of proteins “may influence the immune response, including the stimulation of protective immunity after a single vaccination.”
INFLUENCE OF SIZE AND BREED
In multivariable analyses, adjusting for sex, neuter status, age, weight, breed, and number of vaccinations, significant differences were observed between subgroups within each variable. The odds of a AEs were higher in spayed dogs compared to entire male dogs.
The probabilities were greater for females than for males of the same neuter status and higher for spayed/neutered dogs than for sexually intact dogs of the same sex.
Regarding age, the adjusted odds of adverse events were slightly older for dogs > 9 months to 1.5 years than for dogs ≤ 9 months (reference group). The odds of an AE were significantly lower for dogs > 2.5 years compared to younger dogs. Besides, dogs weighing ≤ 5 kg were almost twice as likely to develop AD compared to dogs weighing > 45 kg.
Finally, race was the variable with the greatest disparity in AD rates between subgroups, with the higher rates observed for french bulldogs y los dachshund. Also, the increasing the number of vaccines administered in a single visit increased AEs with an approximately 25% increase in the odds of an AE with each additional vaccine added.
Given that decreased body weight was also associated with increased rates of AD overall, these two findings support, according to the authors, a possible relationship between the occurrence of adverse events and the amount of vaccine antigens administered in relation to body weight“although this relationship appeared to be minimal in dogs weighing > 15 kg.”
Awareness of the risk of adverse events in smaller dogs “may lead to limiting the number of vaccines co-administered, at least in certain breeds.” This could be due to the increase in visits necessary to complete vaccination protocols.
However, the authors clarify that “the volume of vaccine given to smaller dogs should not be reduced (e.g., give half the manufacturer’s recommended dose), as no efficacy studies have been conducted on this issue in protecting against disease.”
Given these findings, they point out that “information on risk factors can be use to update vaccination protocols and client communication”, and they add that “the differences between races may indicate that genetics is the main risk factor for adverse reactions to the vaccine after the type of vaccine.”
2023-10-09 06:13:21
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