Vaccines are a beneficial medical intervention. They are administered with the goal of improving immunity and decreasing the risk of infection to a specific disease. This is accomplished by administering a small amount of a modified pathogen or a component of a particular pathogen to a patient. The patient’s body responds to the foreign pathogen as it would to any foreign material, by activating the immune system to recognize the foreign pathogen, destroying it and creating a record of it in case the body encounters the pathogen at a later time. Understanding how a vaccine works and why it is given demystifies vaccination and facilitates the appropriate use of vaccines.
How a vaccine works
Vaccines are created either from intact viruses, bacteria, toxins or other microbes. Prior to administration they are attenuated or deactivated by either killing the agent or growing the pathogen until it can no longer cause disease. An important part of this process is making sure that the modified version of the pathogen is physically similar to the real pathogen so that the immune system does not recognize each as distinct entities.
When the vaccine is administered, local immune cells pick up the pathogen particles and internalize it so that they can process the pathogen particle into a form that other immune cells can easily recognize. The immune cell then places the processed pathogen particle onto its cell surface and travels to a lymph node where it shows other immune cells the foreign pathogen particle. Other immune cells respond to the display of the foreign particle by remembering what it looks like and preparing themselves to wage war against that particular pathogen. The activated immune cells travel to the site of the vaccine administration and disappointedly do not find the anticipated foreign pathogen. So instead of fighting off the foreign pathogen, the immune cells make a record of the foreign pathogen for future reference.
From the time of vaccination to immunization it takes about two weeks for the immune system to be fully effective against a particular pathogen.
Important vaccine questions to consider
• Why does my puppy or kitty need vaccines?
Young animals have not been alive long enough to have received significant exposure to the wide variety of pathogens present to condition their immune system. As mentioned previously, when the immune system encounters a pathogen it creates a record of that pathogen for future reference. Administering vaccines to puppies speeds up the natural process by intentionally exposing the immune system to common pathogen.
• Doesn’t the mother’s colostrum act as an alternative immune system until the puppy or kitty is significantly exposed to a variety of pathogens?
Yes! The mom’s colostrum is rich in antibodies that protect the puppy against some pathogens. Which pathogens the mom’s colostrum protects against depends on what pathogens the mom’s immune system has made a record of. Thus, depending on what pathogens the mom has been exposed to determine which pathogens the puppy will be immune to through the colostrum.
• Why does my puppy or kitty need so many vaccination shots?
Colostrum is a catch-22. It provides puppies and kitties with immunity by neutralizing foreign pathogens, but it will also neutralize the foreign pathogens in the vaccine. When colostrum neutralizes the foreign pathogens present in the vaccine it prevents the puppy’s immune system from appropriately responding to the vaccine. Colostrum’s ability to neutralize foreign pathogens decrease as the puppy grows older. Veterinarians begin to vaccinate at 2-5 months old because this is when colostrum’s ability to neutralize foreign pathogens is decreasing, allowing the puppy and kitty’s immune system to effectively respond to the vaccine. However, exactly when the protection afforded by the mother’s colostrum begins to become less effective varies between each individual. This is why veterinarians administer vaccinations in series. Veterinarian’s want to begin exposing the puppy’s immune system to common pathogens right when the protection afforded by colostrum begins to wane.
• Can my pets still get sick after receiving a vaccine for a specific pathogen?
Unfortunately yes. As with anything, exposure to too much pathogen can cause illness. However your pet will not be as sick if they did not receive the vaccine.
• How often should I “booster” my pets vaccines?
Boostering a vaccine refers to administering an additional vaccine at a later time. Exposing the immune system to the foreign pathogen at a later time reminds the immune system of the previous exposure and updates the immune system’s record. How often a pet should be boostered depends on how effective the vaccine is at creating an accurate record within the immune system. Some pathogens such as the influenza virus change slightly every year requiring annual vaccinations of the most current form of the virus whereas other viruses such as distemper do not change often and can be boostered every 3 years. Specific vaccines should be given annually if your pet is in an area that has a higher than normal incidence of the disease such as Lyme disease or leptospirosis.
• What are core vaccines for dogs?
The American Veterinary Medical Association considers rabies, distemper, parainfluenza, parvovirus-2 and adenovirus-2 as core vaccines in dogs.
• What are non-core vaccines?
Non-core vaccines are given to dogs that are at increased risk for a particular pathogen. The reasons why a dog may be at increased risk for a particular pathogen depends on where the dog lives, amount of exposure to other dogs that may carry pathogen(s) and exposure to other animals that may carry the pathogen(s).
Vaccines are a necessary component of keeping your pet healthy and free of disease. Although they have received considerable controversy, vaccines are considered one of the greatest medical interventions. Since the onset of vaccines, they have prevented significant suffering and death and have contributed to the eradication of several diseases. Not only do vaccinations decrease an individual’s risk of morbidity and mortality they also decrease the prevalence of the disease in the overall population contributing to a healthier pet population.