Vaccinations-Risk or Reward?

Equine vaccinations and other preventive medicine present a classic risk-reward scenario. Post vaccination reactions vary from nothing to soreness and swelling at the vaccination site accompanied by a fever and in a few cases, a severe allergic or anaphylactic reaction. Obviously the post vaccination reactions are undesirable and often dangerous. So why vaccinate? First the incidence of severe reactions is rare; 90+% of vaccinates show little if any after effects. A few horses have some transient swelling and a light fever; this is the most common adverse reaction. Severe anaphylactic allergic reactions are very rare. Second the diseases that one vaccinates for are much worse than any adverse reaction to a vaccine. Anyone who has witnessed a non-vaccinate with tetanus, WNV, EEE, WEE, rabies, or severe influenza or rhinopneumonitis has no doubt as to the benefits of vaccinating against these diseases. The vaccines have become a victim of their own success. They have reduced the incidence of some of these dread diseases to the point where many younger people have never seen them and often they associate vaccinations only with the rare side effects of the vaccine rather than the prevention of the targeted diseases. It’s a classic risk-reward; vaccinate and risk a small chance of adverse reaction (a minor risk); don’t vaccinate and risk contracting a deadly disease (a huge risk). Obviously the risk of vaccination is very small while the risk of not vaccinating can be extreme. The reward for vaccinating is immunity from the disease (a powerful reward). The reward for not vaccinating is freedom from rare side effects (a small reward).