So where did you see this warning?
The label says this
Precautions: Store at 2°-8°C. Do not freeze. Use entire contents when first opened. Do not vaccinate within 21 days before slaughter. Contains formalin as a preservative. This product has not been tested in pregnant animals. As with many vaccines, anaphylaxis may occur after use. Initial antidote of epinephrine is recommended and should be followed with appropriate supportive therapy. Do not mix with other products. In case of human exposure, contact a physician.
