Page "Bioterrorism" Paragraph 21

; Smallpox: Smallpox is a highly contagious virus.

It is transmitted easily through the atmosphere and has a high mortality rate ( 20-40 %).

Smallpox was eradicated in the world in the 1970s, thanks to a worldwide vaccination program.

However, some virus samples are still available in Russian and American laboratories.

Some believe that after the collapse of the Soviet Union, cultures of smallpox have become available in other countries.

Although people born pre-1970 will have been vaccinated for smallpox under the WHO program, the effectiveness of vaccination is limited since the vaccine provides high level of immunity for only 3 to 5 years.

Revaccination's protection lasts longer.

As a biological weapon smallpox is dangerous because of the highly contagious nature of both the infected and their pox.

Also, the infrequency with which vaccines are administered among the general population since the eradication of the disease would leave most people unprotected in the event of an outbreak.

Smallpox occurs only in humans, and has no external hosts or vectors.