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
- Immunodeficiency
- Allergies to
polymyxin B, streptomycin, tetracycline, or neomycin
- Eczema – including
those who do not currently have symptoms
- Pregnancy
- 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:
- If the number
of cases grows too large for effective contact tracing,
- If the number
of new cases after two generations fails to decline,
- 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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