Eradication

As the number of new cases continues to dwindle, one of the most important questions for the future is whether SARS can be eliminated or eradicated from its new human host. Experience with many other infectious diseases, including smallpox and poliomyelitis, has demonstrated that complete eradication of an infectious disease is possible only when three precise requirements can be met (WHO Update 84):

1)An effective intervention capable of interrupting transmission – ideally, a vaccine – must be available.

2)Easy-to-use diagnostic tools are needed, with sufficient sensitivity and specificity to detect levels of infection that can lead to transmission of the disease.

3)Finally, infection of humans must be essential to the life-cycle of the causative agent – if the chain of human-to-human transmission is broken, the agent cannot survive. Existence of an animal reservoir greatly complicates eradication, but does not preclude it, provided that interventions exist to break the chain of transmission in the animal species as well.

To achieve eradication at the global level, the control intervention must be safe, simple, and affordable. Current control measures for SARS, including case detection and isolation, tracing and follow-up of contacts, and quarantine, are effective but extremely time-intensive, costly, and socially disruptive. Few, if any, countries can sustain such efforts over time (WHO Update 84).