Smallpox Outbreak Control Activities and Strategies

Surveillance and Containment (Ring Vaccination) (22:V1:51)

Description

Surveillance and containment is the central strategy for containing an outbreak of smallpox. It is sometimes called ring vaccination too, although that term leaves out the infection control measures that also need to be implemented. The principle behind this strategy is to identify cases of smallpox, vaccinate their household and other close contacts, then also vaccinate close contacts of the primary household and close contacts to the case. Then, if the primary contacts developed smallpox despite vaccination, their close contacts would already be protected and the chain of transmission would have been broken.

Steps for Surveillance and Containment:

  1. Search for cases.
  2. Provide a ring of immunity around each case. This includes vaccinating close contacts and close contacts of contacts.
  3. In order to control disease the most efficient use of vaccine is required as is minimizing adverse reactions.

Surveillance (22:V1:52)

Surveillance is important both before a smallpox outbreak and after a smallpox outbreak. In the pre-event situation, we might just be able to look for the typical, ordinary type smallpox cases. We will need to confirm the initial case by laboratory testing. A positive laboratory result will lead to the surveillance and containment strategy with vaccination. In the post-event setting, we will refine our ability to clinically diagnose cases, so we will attempt to find all cases, both typical and atypical. Since the smallpox activities are already underway and we will know that smallpox virus is again circulating, a clinical diagnosis of smallpox is enough to being vaccination of the contacts. In this setting, we will need active surveillance, with contact being made daily with hospitals in order to track the progression of the outbreak.

Pre-Event Surveillance Steps include:

  1. Identifing cases with typical presentation.
  2. Rapid laboratory confirmation.
  3. Confirmation initiates contact vaccination.
  4. Passive with more specificity.

Post-Event Surveillance Steps include:

  1. Identify all potential cases (typical/atypical).
  2. Clinical diagnosis can initiate contact vaccination.
  3. Active with increased sensitivity. 
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