This paper reflects on public health considerations on the voluntary release of anti-fertility
vaccines for wildlife in the environment. The World Health Organization (WHO) has established a variety of recommendations on safety and efficacy requirements for the voluntary release of
rabies vaccines used for oral immunization of animals. These requirements cover aspects of control of
rabies and possible
biological consequences in the target population. They also deal with the protection of the health of humans and other non-target species that might come into contact with the different oral
rabies vaccines used in various parts of the world. These recommendations are laid down in several WHO publications. They are specific to the disease concerned, the target animal reservoir, the relationship and types of contact between humans and target animals, the
vaccines and baits used and the respective conditions of oral immunization of wildlife in densely-populated areas. Many of these recommendations also apply to the development and application of
contraceptive vaccines for wildlife carnivores. Additional safety requirements concern the transmissibility of the
antigen, the reversibility of the intervention within an individual animal and in animal populations, as well as the species specificity of the
antigen used. The management of animal populations that are reservoirs for
zoonotic diseases is a possible means by which diseases that are transmissible from animals to humans could be prevented. Oral
contraception by means of
vaccines is an appealing method, provided that requirements for protecting public and animal health, as well as ensuring environmental safety, are precisely defined and strictly adhered to.