You have to know what to expect from vaccines if you’re going to use them successfully, says veterinarian Sam Barringer, with Pfizer Animal Health. “When things are going well, vaccines get too much credit,” Barringer claims. “When things are going badly, vaccines also get too much credit.”
Vaccines have limitations, and it’s unrealistic to think they offer absolute disease control 100 percent of the time. Many vaccines provide protection for a year or less.
Also, there are many more diseases than there are vaccines on the market.
So, what should you expect from a product designed to produce immunity in host animals? You should expect it to stimulate the appropriate immune response in animals for the antigen being vaccinated against, notes Barringer. It should limit the frequency and severity of the disease, with minimum side effects. It should protect against a disease challenge on a herd level, but not necessarily on an individual animal level.
“A few animals may get sick, either from the initial vaccine injection or from a disease challenge,” says Barringer. “That’s to be expected.”
But sometimes those few affected animals become many affected animals. Vaccines fail for a variety of reasons, but the most common include:
Insufficient time to develop immunity before a disease challenge surfaces.
Overwhelming disease challenge.
Duration of immunity is too low.
Differences between vaccine antigens and the field strain that’s causing the disease.
Herd management issues, like inadequate nutrition, excessive animal stress, improper booster timing or poor colostrum management.
“Vaccines are an excellent tool when management is in order,” notes Barringer, “but when management has holes, you will have problems with a vaccination protocol. If you’re practicing good biosecurity, you’ll help manage pathogens and improve your vaccination program’s success rate.”
You need to monitor vaccination programs for adverse animal reactions. Some reactions are more severe than others, but be aware that some vaccines in some animals result in immune suppression, productivity set backs, vaccine hypersensitivity, multiple vaccine-induced problems and injection-site lesions.
Be sure to read the product label for withdrawal times.
Finally, learn more about the vaccine you’re using. Just because a vaccine is licensed doesn’t mean it will be effective in your herd, notes Barringer. “If you’re using a vaccine, look for independent, peer-reviewed research that shows possible outcomes.”