Acceptable levels of endotoxin in vaccine formulations during preclinical research

This brief commentary reviews endotoxin levels of commercial vaccines and puts them into context for the preclinical researcher working in vaccines. Vaccines are not required to adhere to endotoxin levels as outlined in the United States Pharmacopoeia. Vaccine manufacturers have to show that the vaccine is safe and efficacious in clinical trials. Endotoxin limits are typically lot release specifications for most vaccines, but these values are not available to most researchers designing preclinical experiments. The limits outlined are calculated from endotoxin levels found in a variety of vaccine types such as gene vectors, recombinant subunits, polysaccharide, live attenuated, inactivated and toxoid vaccines. It is clear that certain families of vaccines such as toxoids contain much higher levels of endotoxin, where others such as purified recombinant subunits and gene vectors may contain very low levels.