Vaccination against smallpox is assumed to provide protection against human<unk>  infection, because they are closely related viruses and the vaccine protects animals from experimental lethal<unk>  challenges. This has not been conclusively demonstrated in humans, because routine smallpox vaccination was discontinued following the apparent eradication of smallpox and owing to safety concerns with the vaccine. Smallpox vaccine has been reported to reduce the risk of<unk>  among previously vaccinated persons in Africa. The decrease in immunity to poxviruses in exposed populations is a factor in the prevalence of<unk> . It is attributed both to waning cross-protective immunity among those vaccinated before 1980 when mass smallpox vaccinations were discontinued, and to the gradually increasing proportion of unvaccinated individuals. The United States Centers for Disease Control and Prevention (CDC) recommends that persons investigating<unk>  outbreaks and involved in caring for infected individuals or animals should receive a smallpox vaccination to protect against<unk> . Persons who have had close or intimate contact with individuals or animals confirmed to have<unk>  should also be vaccinated. The CDC does not recommend pre-exposure vaccination for unexposed veterinarians, veterinary staff, or animal control officers, unless such persons are involved in field investigations.
Monkeypox
Smallpox
Khat
Chickenpox
Riken
Crack cocaine
Keldur
Street medic