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I missed that original quote in Howard's post, but
you're right, Jennifer, that this figure is likely not the actual "efficacy" of
the vaccine. What the 97% figure likely reflects is the number of
vaccinated individuals nationwide who do not get sick. Many of them would
not have gotten sick anyway, because they were never exposed. If I
vaccinated my horses here, the "efficacy" would be 100%. But that is a
misuse of the word. What "efficacy" means is the number of vaccinated
horses that will not get sick when faced with an actual infective exposure to
the disease, adjusted for the morbidity rate (the number of horses exposed
that will actually get sick under natural conditions). I don't think there
are enough numbers to pin down a really accurate efficacy for this vaccine, but
veterinarians in areas where there is a high exposure rate figure that the
actual efficacy is something closer to 70%.
Heidi
"The efficacy of the vaccine is running about 97 per cent,
nationally.
Howard, I didn't read in your post how 'they' are measuring the vaccine's
efficacy. The uneducated person might assume that veterinary science and
its research are perfectly done and without bias. I (and I hope you do
too) know better. The problem is that people forget the difference
between INCIDENCE (the number of patients who actually get sick from a
disease) and PREVALENCE ( the actual number of patients who have had a
measurable exposure to an illness, sick or not). The latter is hard to
calculate without testing alot of healthy subjects, both vaccinated and
non-vaccinated.
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