Failures in Vaccination

Hello Colleagues and friends!
A lot of people are wondering why vaccines don't work at protecting animals and providing them the immunity desired. Some people blame the Vets, some people blame the labs who produced the vaccines, well here are a couple of things to keep in mind so we can perhaps avoid them and keep our furry patients with high levels of immunity, check it out!

Some times the failure comes within something as simple as the incorrect administration of the vaccines.
For example: a live vaccines may have died as a result of poor storage (under the wrong temperature, or a lot of temperature changes along the transportation), the use of antibiotics in conjunction with live bacterial vaccines, the use of chemicals to sterilize srynges, or the excessive use of alcohol when swabbing the skin.
Sometimes, animals given vaccines by nonconventional routes may not be protected. When large flocks of poultry or mink are to be vaccinated, it is common to administer the vaccine either as an aerosol or in drinking water. If the aerosol is not evenly distributed throughout a building, or if some animals do not drink, they may recieve an insufficient vaccine dosage. 
Animals that subsequently develop disease may be interpreted as cases of vaccine failure.

However, sometimes there is a correct administration, but a failure to the response. This means that the vaccine may actually be ineffective, the method of production may have destroyed the protective epitopes, or there may simply be insufficient antigen in the vaccine. 
Anyhow, this type of problems are not that common, we can always avoid them by using vaccines from reputable labs and manufacturers.

More commonly, an animal may simply fail to set an immune response. Let's not forget that the immune response is a biological process, and it never guarantees absolute protection, and it is never equal in all members or a vaccinated population.

This is because the immune reponse is influenced by a large number of genetic and enviromental factors, the range of immune responses in a large random population of animals tends to follow a normal distribution. This means that most animals respond to antigens by setting an average immune response, whereas a few will set an excellent response and a small proportion will set a poor immune response. 
This group of poor responders may not be protected against infection in spite of having received an efective vaccine. Therefore, it is impossible to protect 100% of a random population of animals by vaccination.
The significance of the unreactive portion of this population will depend on the nature of the disease.
For highly infectious diseases against which herd immunity is poor and in which infection is rapidly and efficently transmitted such as foot-and-mouth disease, the presence of unprotected animals could allow the spread of the disease and would thus disrupt control programs. Likewise, problems can arise if the unprotected animals are individually important; for example, pets.

In contrast, for diseases that are inefficiently spread, like rabies, 70% protection may be sufficient to effectively block disease transmission within a population and may therefore be quite satisfactory.
Another type of vaccine failure occurs when the normal immune response is suppresed. For example: heavily parasitized or malnourished animals may be immunosuppressed and should not be vaccinated. 
Some virus infections induce deep immunosuppression. 
So that is why animals with a major illness or high fever should not be vaccinated unless for a compelling reason. 
Animals that are stressed may have a reduced normal immune response, probably because of increased steroid production; some examples of such stress include pregnancy, fatigue, malnutrition, and extremes of cold or heat.

But guess what, those are not the only cases, sometimes everthing can function properly, sometimes we use the correct administration and there is a correct response, however, even animals in adecuate dose of an effective vaccine may fail to be protected because maybe the vaccinated animal had been incubating the disease before the inoculation. 
That's right, some times the vaccine may be given too late to affect the course of the disease.
In other scenarios, the vaccine contains the wrong strain of organisms or even the wrong antigens (non protective).

So this is why, always in consultation, before you take an animal to give the due shots, first ask how long has the owner had it, if it has had contact with other animals, and if it's been less than 15 days, the animal should not recieve it's shots, just to make sure you know...

So what are your thoughts on this? Have you had any situation where the vaccines didn't work as expected? Has it ever happened to you that you vaccinated an animal and it gets sick right away?
This are just common failures, and we can always keep on learning.
So if you liked this post, share it with your colleagues!


MVZ Carolina Pruneda