My birds are dying in large numbers. Experts say they are suffering from New Castle disease. But I had already vaccinated them against New Castle. What makes vaccines fail?
Answer: There are several factors that can make a vaccine fail. Most common is the temperature at which the vaccine is stored.
Most vaccines need to be maintained in a cold, if possible refrigerated, environment. High temperatures are likely to reduce the vaccine’s effectiveness. Sometimes vaccines fail because the wrong dosage was used, or the farmer did not follow the accompanying instructions.
For instance, if the vaccine was meant to be put in water that birds can finish in two hours, it is dangerous to put it in water that birds will take a whole day to finish. By the end of the day it will no longer be a vaccine but poison.
Also, a vaccine meant to be administered such as an injection should never be put in drinking water. However, farmers sometimes change these methods for convenience.
Also, young chicks below five weeks respond less readily to vaccination than older birds. The immunity the chicks carry from their mothers may make the vaccine less effective.
Birds that are already infected may not benefit from vaccination and in other instances, might even get worse.
Stressful conditions such as overcrowding, temperature extremes or poor feeds might also undermine the vaccine’s effectiveness.
Man-made errors such as wrong method of administration, poor planning and contamination can all lead to vaccine failure.