Human and animal vaccine contaminations.

Vaccination is one of the most important public health accomplishments. However, since vaccine preparation involves the use of materials of biological origin, vaccines are subject to contamination by micro-organisms. In fact, vaccine contamination has occurred; a historical example of vaccine contamination, for example, can be found in the early days of development of the smallpox vaccine. The introduction of new techniques of vaccine virus production on cell cultures has lead to safer vaccines, but has not completely removed the risk of virus contamination. There are several examples of vaccine contamination, for example, contamination of human vaccines against poliomyelitis by SV40 virus from the use of monkey primary renal cells. Several veterinary vaccines have been contaminated by pestiviruses from foetal calf serum. These incidents have lead industry to change certain practices and regulatory authorities to develop more stringent and detailed requirements. But the increasing number of target species for vaccines, the diversity of the origin of biological materials and the extremely high number of known and unknown viruses and their constant evolution represent a challenge to vaccine producers and regulatory authorities.