Isolation Strategies to Contain an Outbreak

Vaccination of Contacts of Contacts

The contacts of contacts are those who are household members of contacts to a smallpox case. Those without contraindications should be vaccinated. Unlike in the instance of direct contacts, the contact’s household members who have a contraindication to the vaccine are not as at high risk. They should not be vaccinated and should avoid the contact for 18 days.

Contraindications for Vaccination of Contacts of Contacts

  1. Immunodeficiency
  2. Allergies to polymyxin B, streptomycin, tetracycline, or neomycin
  3. Eczema – including those who do not currently have symptoms
  4. Pregnancy
  5. And any acute or chronic skin condition. Once those with acute symptoms are resolved, they can be vaccinated.

It’s important to note that those with immunodeficiency and eczema also have a risk of accidental inoculation from those who’ve been immunized. These contacts of contacts should consider removing themselves from the household until all the scabs have fallen off of all those who have been vaccinated.

High-Risk Priority Groups for Vaccination

Anyone else who may have had exposure to the initial virus release, if they are not already displaying symptoms is considered high-risk. Anyone who transported the patient to the hospital and took care of him medically; including the public health workers who are investigating the case is considered high-risk. Laboratory personnel who handled the patient’s lab work are also considered high-risk. Other high-risk groups include support staff in the hospital who have exposure to the linens, clothes, and waste from the patient’s medical care. Other groups to now consider would include the response personnel who would manage additional cases, and other at hospitals who may have to assist in the event of a large outbreak.

Vaccine Administration Support

In order to immunize these contacts, you will need to establish vaccination sites. Clinics will need to be established for contacts and healthcare personnel. Establish central clinic sites will minimize vaccine wastage. However, it will be important to evaluate whether or not vaccine supplies and personnel available can make it possible for vaccine to be taken directly to the homes of the contacts.

No matter what method of vaccination you choose, establishing an adverse events reporting system will be key; as will creating some way to ensure all those exposed are either vaccinated or managed appropriately.

Vaccine Clinics

Due to the limited vaccine supply, planning in the United States has centered around vaccination clinics, rather than having workers carry vaccine directly to immunize contacts.

There are a number of advantages of planning vaccination around vaccination clinics. This setup allows us to minimize vaccine wastage. With 100 doses in a vial, fewer vials can be opened and then used up. In addition, there is reason to suspect that in an outbreak situation, demand for the vaccine could mean that there would be those who would demand the vaccine, which may be limited, or who would try to obtain the vaccine to sell it. Public health officials might also be in the situation where drug control regulations require extensive counseling and paperwork that can be more easily managed in the clinic setting.

Supplemental Strategies

Mass Vaccination - While the United States will be relying primarily on ring vaccination if an outbreak of smallpox were to occur, broader vaccination might be considered:

  1. If the number of cases grows too large for effective contact tracing,
  2. If the number of new cases after two generations fails to decline,
  3. If the vaccine stores used under the ring vaccination process declines by 30% without a decline in cases; indicating that contact tracing is not working.

Dilution of Vaccine – Because of the limited supply of vaccine available, the United States undertook studies to see if existing vaccine could be diluted to stretch the vaccine supply. Evaluation of the efficacy of the vaccine at both 1:5 and 1:10 dilution indicated similar rates of takes at around 95% of those vaccinated. Diluting the vaccine supply might be a way to stretch limited stores when the vaccinee has not been directly exposed to a case, such as in the case of mass vaccination.

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