With the advent of new commercial modified live vaccines, we will need to be particularly vigilant to ensure that we maintain our good safety record. Lunn and others agree that owners should know about the diseases that threaten their horses and understand the risks of those diseases and the risks of the vaccines when deciding what to vaccinate against. That viewpoint probably is naive. That if it doesn't help, it won't hurt. That's not the case.
Vaccines are biological drugs.
They can cause harm just like a pharmaceutical drug. If the product is good and the animal really needs it, then it should be given, given appropriately, and given as often as needed. If the risk is very low or the product is not very good, then make sure the animal doesn't get it, because the risk may be greater than the benefit. Very often, those individuals are not looked upon with favor, and their views are not popularly held. This is a very difficult situation as you get people on the other extreme who don't want to give any vaccines.