Howdy. My name is Ian Tizard,
and I'm a Professor of Immunology at Texas A&M University.
What I want to talk about today is problems associated with vaccines;
vaccine failures- when they don't work-
and vaccine adverse effects.
Now let me say first of all,
that these are minor problems in the big scheme of things.
Vaccines are incredibly effective.
They are critical for the maintenance of the health of your animals,
be they pets or livestock.
So, don't exaggerate the importance of failures and adverse events,
but they do happen and veterinarians need to be aware of them.
So, vaccines do not always work.
One cannot guarantee that a vaccine will work,
and there are several reasons for this.
So, when we look at the failures of vaccines,
when they don't appear to work,
there are several ways to investigate the case and determine what the problem is.
First of all, it could be the fault of the person administrating the vaccinating.
In other words, are they going with the proper instructions?
Did they use the right dose or the right route?
Did they vaccinate against the wrong disease?
Did the series get completed?
Sometimes when a series of vaccine doses have to be
given and the patient or the client has to come back at intervals,
they forget, and so the complete series is not finished.
One of the problems also related to that is the fact that maybe the interval
between doses of the vaccine is too long and they don't work very well.
So, if you're investigating the vaccine that doesn't seem to work,
then that's the first thing to look at.
The other way to look at it is,
of course, the vaccine itself.
Is that the right vaccine?
Does it contain the right organisms?
Is that, for example, the right strain?
If the vaccine is against strain A,
but the problem on the farm is strain B,
then it's not going to work.
Have the vaccines been stored properly?
Have they been kept cold?
Many vaccines are very temperature sensitive and if they're
not handled in the correct refrigerator at the right temperature,
they're going to break down fast.
Of course, the obvious thing is,
have they gone beyond their expiration date?
Vaccines don't last forever.
So, check the expiration date and discard any unused vaccines.
But, what I want to focus on is, in fact, the problem with the animal.
In fact, this simply boils down to biological variation.
I'll talk about that in a second.
We'll talk about other things like,
is the animal already incubating the disease?
What about those antibodies from the mother that block the response?
Is the animal immunosuppressed in some way; is it stressed?
Is it unhealthy? Let's look at some of those.
But, first of all,
let's look at the normal biological variation because
this is by far the most important cause of vaccine failure.