Eradication
of smallpox was a medical triumph over a disease that
had been a human scourge for centuries.1
While the smallpox virus has been confined to research
laboratories, a renewed fear of the disease has emerged
as a tool of bioterrorism.2
This concern has not just developed since the events
of September 11, 2001. In fact, an exercise called
“Dark Winter” in June 2001 simulated a
covert smallpox attack on the United States under
the premise that there was insufficient vaccine and
no prior vaccinations had taken place.3
This scenario resulted in significant morbidity and
a presumed 30 percent mortality (an historical average).
To meet the potential dreaded consequences of a smallpox
attack, President Bush announced on December 13, 2002,
recommendations for a smallpox readiness program that
included the formation of health care response teams.
These teams will be composed of health care workers
and other critical personnel who will administer care
to victims in the event of an attack.
Health departments around the country are now developing
and implementing readiness programs. As health care
workers, we need to become knowledgeable about the
disease. We must understand who can be vaccinated,
the appropriate care of a vaccination site and the
risks of our own vaccination to our patients, both
healthy and immunocompromised, as well as our families
and ourselves — for while vaccination is relatively
safe, it is not risk-free.
Smallpox is caused by the variola virus. It is spread
by respiratory mechanisms such as coughing that release
droplet nuclei and aerosols or by direct contact with
an infected person or items such as contaminated clothing
or bed linens.1 Following
an incubation period of seven to 17 days, a prodrome
consisting of fever, malaise, headache and backache
occurs. An oral enanthem appears that signals the
onset of oropharyngeal infectiousness. A rash then
appears that at first is macular, then papular and
progresses to the formation of vesicles, then pustules.
Next, pustules crust over and fall off, leaving the
characteristic disfiguring scars of smallpox. A patient
is considered infectious until the pustules have scabbed
over and the scabs have fallen off, and patients must
remain in isolation until this phase is complete.
The fatality rate of smallpox can reach 30 percent
and is associated with toxemia, intravascular volume
depletion and, occasionally, a hemorrhagic diathesis.1,2
The last natural case of smallpox occurred in 1977.2
Health care workers immunized against smallpox must
still employ respiratory and contact isolation precautions
when dealing with infected people.5
Since there is no effective treatment for smallpox,
people need to be vaccinated with the live vaccinia
virus. While related to variola virus, the vaccinia
virus does not cause smallpox, but it does help the
body to develop immunity to the smallpox virus. The
vaccine distributed for use today is a relicensed
vaccine of the original calf-derived Dryvax®
product from Wyeth-Ayerst. This vaccine has been in
storage since 1985 and is derived from the New York
City Board of Health-strain of live vaccinia virus.
The vaccinia strain used in this preparation has been
shown to cause less adverse effects than other vaccine
strains.6
Vaccination ceased in the United States in 1972.2
Immunity after vaccination lasts three to five years,
although it is thought that immunity may last longer.
Even though immunity wanes, it still offers some degree
of protection as demonstrated by a decreased mortality
rate among individuals who develop smallpox but have
a history of vaccination. For those never vaccinated
or with distant vaccination, the vaccine must be given
within three to four days after exposure to smallpox
to protect against infection.2
Individuals who were vaccinated longer than three
years ago will require revaccination.
Once an individual is vaccinated, it can take three
weeks from the initial appearance of a macule (three
to seven days) at the vaccine site to a complete response,
which ultimately results in a scab. Until the scab
falls off at approximately three weeks, the vaccine
site should be considered contagious.1
This highlights the importance of strict hand washing
and meticulous care of the inoculation site and all
materials that come in contact with the vaccination
site. In many instances, vaccine recipients may be
required to report to designated health care officers
for care of the vaccine site prior to their workday.
In an attempt to eliminate the possibility of transmission
of vaccinia, the vaccine site must be properly covered,
usually with gauze and a semipermeable dressing and
clothing over the dressing. The Centers for Disease
Control and Prevention recommends that during the
time of potential infectivity, vaccinees and/or guardians
should keep the vaccine site covered and should not
touch, scratch or rub the vaccine site (the area tends
to be itchy) while avoiding contact with susceptible
individuals.5,6 The
vaccinee should avoid touching, rubbing or otherwise
performing any maneuvers that might transfer vaccinia
virus to the eye, surrounding or distant skin, or
mucous membranes. The vaccine site dressing or covering
should be discarded in a closed plastic bag. After
any contact with the vaccine site or covering, one
should thoroughly wash his or her hands with soap
and warm, running water.5,6
Since the vaccine is live, a major concern during
the vaccination process is transmission of vaccinia
through inadvertent inoculation during the time the
vaccinated person is infectious. Infection can occur
by spreading from the site of inoculation to nonvaccinated
individuals or by autoinoculation from the site of
vaccination to other parts of the body of the vaccinated
person. There have been several well-documented cases
of inadvertent inoculation from touching the dressings
or clothing that was in contact with the vaccination
site.7 The eye is a
common site for autoinoculation. Ocular vaccinia manifestations
include keratitis, conjunctivitis and blepharitis.
Unintended inoculation of others can result in potentially
life-threatening systemic infection.
All potential vaccine recipients should be screened
for contraindications to voluntary vaccination, including
a history of skin conditions such as eczema, atopic
dermatitis, impetigo, psoriasis, unhealed burns, contact
dermatitis or active chickenpox. In addition, contraindications
to vaccination include pregnancy (or plans to conceive
within a month), breastfeeding mothers, immunosuppression
(e.g., cancer therapy, status post-transplant, systemic
or possibly inhaled steroids, HIV, AIDS, eye disease
of the conjunctiva that may result in itching of the
eye and therefore increase the risk of autoinoculation,
eye disease requiring topical steroid drops and children
less than 12 months of age.4,5,7,8
The risk in individuals with immunosuppression is
due to the possibility of progressive systemic infection
from vaccinia virus because of poor immune localization
to the vaccination site.8
Household contact with anyone having any of the above
conditions also precludes voluntary vaccination due
to the risk of transmission except for children less
than 12 months of age. The risk of transmission is
low in settings where meticulous care of the vaccination
site is taken. Additional contraindications to smallpox
vaccine include hypersensitivity to any of the vaccine
components such as streptomycin, tetracycline, polymyxin
or neomycin. Chickenpox vaccine should not be given
within 30 days of smallpox vaccine because of the
difficulty in differentiating the rash of chickenpox
from early vaccinia.5
While many relative contraindications to pre-exposure
vaccination exist, exposure to the smallpox virus
changes the risk-to-benefit ratio of vaccination given
the potential lethal consequences of smallpox infection.
Reactions to vaccination tend to be less severe in
those who have received prior immunization. However,
mass vaccination programs stopped about 30 years ago
in the United States.4
The adverse reactions associated with the smallpox
vaccine can be mild, consisting of a rash at the site
of inoculation and associated with fever, headache
and malaise. There are a variety of other reactions
delineated in the 19689 survey of American physicians
in which all the recipients had been vaccinated for
the first time. They were divided into two categories:
1) serious but not life-threatening reactions and
2) life-threatening reactions.
The serious but not life-threatening reactions were
the most common and in order of decreasing frequency
were (per million vaccinees):
| Inadvertent inoculation |
529 |
| Generalized vaccinia |
241 |
| Erythema multiforme |
164 |
| Total |
935 |
|
Life-threatening reactions were less frequent and
in order of decreasing frequency were (per million
vaccines):
| Postvaccinal encephalitis |
12 |
| Progressive vaccinia |
1.5 |
| Eczema vaccinatum |
38.5 |
| Total |
52 |
| Death |
1.5 |
|
Recent experience with the smallpox virus in Israel
has demonstrated an overall complication rate, including
the rate of severe complications (postvaccinal encephalitis
and permanent neurologic sequelae), that is consistent
with previously published data in Israel and the United
States.10 The recent
Israeli data is useful to review since it includes
a proportion of the population that had not previously
received smallpox vaccine, further demonstrating that
smallpox vaccine administered in a controlled setting
is relatively safe. Extrapolation as to what we can
expect in the United States once the first phase of
the vaccine program begins is probably reasonable
even though the vaccines administered in Israel and
the United States are different preparations.
Frequently Asked
Questions from Health Care Workers Concerning
Smallpox
The New York City Department of Health
and Mental Hygiene has compiled a list
of “Frequently Asked Questions About
Smallpox Vaccine and the Voluntary Program
for Vaccination of Health Care Smallpox
Response Teams.”11
It offers answers to some questions that
physicians and others have asked about
the vaccination process. Two of the 46
questions and answers are listed here.
Will I still be able to take
care of patients after I get the smallpox
vaccine?
Yes. It is acceptable to continue work
after getting the smallpox vaccine as
long as your vaccine site is covered with
the correct type of dressing (gauze and
a semipermeable dressing), you wear long-sleeved
shirts or sweaters, the vaccine site is
checked every day before you work, and
you are careful to wash your hands after
touching the vaccine site or dressing,
even if you are wearing gloves.
The vaccine site will be checked before
every work shift by health professional
employees or other staff designated by
your hospital to do these checks until
your scab falls off. If you take proper
care to wash your hands whenever touching
the vaccination site or the dressing and
before and after seeing any patient, there
should be little risk to your patients,
even to those who have weakened immune
systems (e.g., HIV infection or cancer
patients). In the past, the spread of
vaccinia virus from the vaccine site to
patients in the hospital was very rare.
However, if any of the following occur,
the hospital will advise you not to come
to work:
| • If you are ill and physically
unable to work. |
| • If your vaccine site becomes
very red and swollen with pus and
cannot be covered adequately with
a dressing |
| • If you do not follow infection
control measures of washing your
hands with soap and water (or an
approved hand-hygiene disinfection
product) after touching your vaccine
site or the dressing and before
and after every time you touch a
patient. |
Some hospitals may, depending on your
job duties, decide to temporarily re-assign
you to a different job or to put you on
leave until the vaccine-site scab falls
off. This decision will be made by each
hospital and may apply to certain staff
only.
Why is it OK for me to work
with patients who are likely to have health
problems (such as HIV, cancer, pregnant
women and patients with eczema) after
I get smallpox vaccine but not OK for
my close household or intimate contacts
to have one of these diseases or conditions?
In the hospital setting, it is much less
likely for staff to have close, prolonged
intimate contact than it is at home. Household
or other close contacts are more likely
to spend longer periods of time with the
person who is vaccinated as well as to
be more intimate than health care workers
and their patients. Because of the special
precautions used in hospital settings
(which are not as easy to follow in household
settings), spread of the vaccinia virus
(in the vaccine site) from health care
providers to their patients has been low
in the past. Also, as long as the vaccine
is covered well by a dressing (gauze bandage
and semipermeable dressing) as well as
your clothing and you are sure to wash
your hands thoroughly before and after
touching the vaccine site and dressing,
and before and after touching your patients,
the risk to your patients is thought to
be low. In a recent study, no vaccine
virus (the vaccinia virus) was found on
the outside of the dressing (gauze bandage
and semipermeable dressing) of any vaccinated
person.
As physicians, we will be called upon
in the event of a bioterrorist event,
and smallpox vaccinations will be offered
to us. Many questions will be raised as
we respond to this call to arms. Resources
such as the Centers for Disease Control
and Prevention Web site <www.cdc.gov/smallpox>
are available to educate us. Knowledge
of the disease, the vaccination process,
its risks and benefits and how it will
affect us, our patients and our families
are important to understand so that each
individual can make an informed decision
as we consider our role in public service
in the effort against bioterrorism.
The fact sheet “Frequently Asked
Questions About Smallpox Vaccine and the
Voluntary Program for Vaccination of Health
Care Smallpox Response Teams” can
be accessed at <www.nyc.gov/html/doh/html/cd/cdsma.html>. |
|
| References: |
| 1. 29 F, Henderson DA, Arita I, Jezek Ladnyi
ID. Smallpox and its eradication. Geneva: World
Health Organization, 1988. <www.who.int/emc/diseases/smallpox/Smallpoxeradication.html>.
Accessed January 27, 2003. |
| 2. Henderson DA, Inglesby TV, Bartlett JG,
et al. Smallpox as a biological weapon: Medical
and public health management. JAMA.
1999; 281:2127-2137. |
| 3. O’Toole T, Mair M, Inglesby TV. Shining
light on “Dark Winter.” Clin
Infect Dis. 2002; 34:972-983. |
| 4. Breman JG, Henderson DA. Diagnosis and
management of smallpox. N Engl J Med.
2002; 346:1300-1308. |
| 5. Centers for Disease Control and Prevention.
<www.bt.cdc.gov/agent/smallpox/index.asp>.
Accessed January 27, 2003. |
| 6. Centers for Disease Control and Prevention.
Smallpox vaccination and adverse reactions.
Guidance for clinicians. MMWR Dispatch.
2003; January 24; 52. |
| 7. Sepkowitz KA. How contagious is vaccinia?
N Engl J Med. 2003; 348:439-446. |
| 8. Moses AE, Cohen-Poradosu R. N Engl
J Med. 2002; 346:1287. |
| 9. Lane JM, Ruben FL, Neff JM, et al. Complications
of smallpox vaccination: National surveillance
in the United States, 1968. N Eng J Med.
1969; 281:1201-1207. |
| 10. Haim M, Gdalevich M, Mimouni D, et al.
Adverse reactions to smallpox vaccine: The Israel
Defense Force experience, 1991 to 1996: A comparison
with previous surveys. Military Med.
2000; 165:287-289. |
| 11. New York City Department of Health and
Mental Hygiene Question and Answer Fact Sheet
for Health Care Workers Considering Volunteering
for the Smallpox Vaccine “Frequently Asked
Questions About Smallpox Vaccine and the Voluntary
Program for Vaccination of Health Care Smallpox
Response Teams.” <www.nyc.gov/html/doh/html/cd/cdsma.html>.
Accessed on December 24, 2002. |
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| |
|
Helene Lupatkin, M.D., is Assistant Professor,
Department of Medicine, Division of Infectious
Diseases, New York University School Of Medicine,
New York, New York. |
|
|
|
Joel
F. Lupatkin, M.D., is Attending Anesthesiologist,
Hospital For Joint Diseases, New York University
School Of Medicine, New York, New York. |
|
| |
|
Andrew D. Rosenberg, M.D., is Chair, Department
of Anesthesiology, Hospital For Joint Diseases
and Associate Professor of Clinical Anesthesiology,
New York University School of Medicine, New
York, New York. |
|
| |
|
Samuel
Hughes, M.D., is Professor of Clinical Anesthesia
and Perioperative Medicine, University of California-San
Francisco, San Francisco, California, and Chair,
ASA Infection Control Task Force. |
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