Chapter 4 Part B: Potential serious adverse events,
with Dr. Brett Petersen.
Postvaccinial encephalitis is an unpredictable,
serious complication with highest rates observed
in primary vaccinees 24 months of age and younger.
It presents with any of a variety
of central nervous system signs or symptoms,
such as altered mental status, ataxia, confusion, paralysis,
seizures, or coma and is a diagnosis of exclusion.
Most cases are believed to result from autoimmune
or allergic reactions, similar
to other postviral central nervous system syndromes rather
than direct viral invasion of the nervous system.
No specific treatment exists
for postvaccinial encephalitis except supportive care.
Approximately 25 percent of vaccinees
with this complication die,
25 percent develop permanent neurological sequelae,
and the remaining 50 percent recover completely.
Eczema vaccinatum is the generalized spread of vaccinia
on the skin of an individual
with eczema or atopic dermatitis.
Patients often have a high fever and malaise
and will have a localized or generalized papular, vesicular,
or pustular rash that can occur anywhere on the body
with a predilection for areas
of previous atopic dermatitis lesions.
Severe cases usually occur among primary vaccinees
and among non-vaccinated contacts with atopic dermatitis
or eczema and are independent of the activity
of the patient's underlying eczema.
Vaccinia virus is readily recoverable from skin lesions.
Prompt treatment with vaccinia immune globulin or VIG
for eczema vaccinatum has been shown to be beneficial
and mortality was reduced from about 40 percent
to 7 percent in one study.
This is a picture of a woman with a history of eczema
who experienced eczema vaccinatum after contact
with her recently-vaccinated boyfriend.
She survived the illness but had extensive residual scarring
of her skin.
Progressive vaccinia, once referred
to as vaccinia necrosum, is a severe,
potentially fatal illness, characterized by a painless,
non-healing vaccination site with progressive necrosis with
or without spread to distant sites.
Progressive vaccinia occurs almost exclusively among
individuals with immunodeficiencies.
This diagnosis should be suspected
if an active vaccination lesion continues to progress
without apparent healing for more
than 15 days post-vaccination.
Progressive vaccinia can occur following revaccination
of individuals who have become immunosuppressed
since their primary vaccination.
Progressive vaccinia may occur more frequently
in today's population, with the greater prevalence of HIV
and post-transplant immunosuppression.
This is a picture of an individual
who experienced progressive vaccinia
after smallpox vaccination.
Fetal vaccinia is a very rare complication
of smallpox vaccination where a fetus may be infected
when a pregnant woman receives smallpox vaccine
and often manifests with skin lesions
and organ involvement of the fetus.
This complication usually results
in fetal or neonatal death.
Fewer than 50 cases of fetal vaccinia infection have been
reported after smallpox vaccination.
The greatest risk for fetal vaccinia is usually following
primary vaccination of the mother in the third trimester.
Smallpox vaccination
of a pregnant woman has not been known to be associated
with congenital malformations or birth defects.
VIG may be considered in a viable infant born with lesions;
however no data exists to determine the appropriate dosage
or for estimating efficacy.
Inadvertent inoculation is the physical transfer
of vaccinia virus from an active vaccination site
onto a second site on the vaccinee
or to close contacts of the vaccinee.
It is listed as a serious adverse event
because this transfer can result in serious complications
and is the most common complication following
smallpox vaccination.
Accidental self-inoculation occurs most often on the face,
eyelid, nose, mouth, lips, genitalia, and anus.
The highest rates are seen among children under 4 years old
and those with disruption of the epidermis.
Self-inoculation usually happens
after the vaccinee scratches the site
because the vaccine lesion itches as it heals.
The secondary lesion typically will look
like the active vaccination site lesion
and is generally self-limited.
However, self-inoculation of the eye may result
in ocular vaccinia and blindness.
Accidental transmission of vaccinia
to non-vaccinated contacts can happen
through close physical contact with an open,
active vaccination site,
particularly during intimate activities
such as breastfeeding or during sex.
Contact with contaminated fomites such as clothes, towels,
or bedding have also been a vehicle for spread
of vaccinia virus to others.
Carefully following proper vaccination site care
instructions and proper handling of contaminated materials,
along with vigilant hand washing,
will significantly decrease the risk of this complication.
Although no reports of death have been associated
with ACAM2000, older smallpox vaccine studies suggest death
resulting from smallpox vaccination is rare,
with approximately 1 death per million primary vaccinations
and 1 death per 4 million revaccinations.
Case fatality rates using the older smallpox vaccines were
highest among the very young and older age groups.
Death was most often the result of postvaccinial encephalitis,
progressive vaccinia, and eczema vaccinatum.
Death has also been reported in close contacts of vaccinees due
to complications as a result of inadvertent inoculation.
Remember, an assessment of risks and benefits must be conducted
when deciding whether
to vaccinate an individual with ACAM2000.
The risk/benefit profile will differ depending
on if a smallpox emergency is in effect,
versus if there is no smallpox emergency in effect.
For example, during a smallpox emergency,
the risks of these serious adverse events may be outweighed
by the risk of experiencing a potentially fatal
smallpox infection.