Questions and Answers about Smallpox and Smallpox Vaccination
September 2002
Smallpox was eradicated from the world in 1977, but the threat of a deliberate release of stockpiled smallpox remains. Even one patient with smallpox would be a public health emergency because (unlike anthrax) this virus can be transmitted through the air, and infection can reach epidemic proportions very quickly.
Vaccinations for first responders and other healthcare workers could start before the end of 2002.
1. When is a patient with smallpox contagious?
From the onset of the rash until the last scab falls off.
2. What is the incubation period of smallpox, i.e., the time from exposure until the first symptoms occur?
7-17 days (the average is 10-12 days). Initially, there is a “febrile prodrome” with fever, headache, and backache. Rash starts ~ 3-4 days after the start of this “febrile prodrome”. Patients are NOT contagious until the rash appears.
3. How do you diagnose smallpox?
Major diagnostic criteria (3) for smallpox (see CDC color algorithm in the ED):
1. Febrile prodrome: occurring 1-4 days before onset of rash. Fever of at least 101 degrees F and at least one of the following: prostration, headache, backache, chills, vomiting, or severe abdominal pain.
2. Classic smallpox lesions (deep seated, firm, hard, round, well-circumscribed vesicles or pustules and as they evolve lesions may become umbilicated or confluent). Lesions start on face, palms, and soles and spread centrally (the opposite of chicken pox).
3. Lesions in same stage of development: on any part of the body (e.g., the face, the arm) all the lesions are in the same stage of development (i.e., all are vesicles, or all are pustules).
Minor Diagnostic Criteria (5) for Smallpox:
Ø Greatest concentration on the face and extremities.
Ø First lesions on the oral mucosa/palate, face or forearms.
Ø Patient appears toxic or moribund.
Ø Slow evolution: lesions evolve from macules to papules to pustules over several days (each stage lasts 1-2 days).
Ø Lesions on the palms and soles.
4. How do you distinguish chickenpox from smallpox?
|
Chickenpox: |
Smallpox: |
|
No or mild prodrome |
Febrile prodrome |
|
Superficial vesicles (dewdrop on rose petal) |
Deep, firm vesicles or pustules |
|
Lesions in different stages |
Lesions all in same stage |
|
Most lesions on trunk |
Most lesions on face & extremities |
|
Rarely toxic |
Usually toxic |
|
Rapid evolution of skin lesions |
Slow evolution of lesions > 2 weeks |
|
Rarely palms and soles |
Often palms and soles |
|
May recall exposure 10-21 days pre-rash |
Exposure 7-17 days pre-fever |
5. Can smallpox be spread by contact with patient’s clothing and sheets?
Yes.
6. If there is no direct skin contact with patient, can you still catch smallpox?
Yes. Smallpox virus (“variola virus”) gets into the air from the oral- respiratory tract, so smallpox can be spread from person-to-person through the air, unlike anthrax. A patient’s cough or breathing can transmit the variola virus on small droplets to other persons.
The highest risk of airborne spread is face-to-face contact within 2 meters (6.5 feet). If you are in the same room as a person with smallpox, but greater than 7 feet away, you are at lower risk of getting infected, but risk is still clearly present.
Wear at least a fit-tested N-95 (“duckbill”) orange mask (same mask as for TB protection) to protect against airborne smallpox.
Touching smallpox skin lesions can also transmit the smallpox virus skin-to-skin, so always wear gloves and follow both contact and airborne precautions.
7. After exposure, can you be protected by a post-exposure vaccination?
Yes. Optimum post-exposure vaccination is within 2-4days of exposure. You have several days after exposure to become protected from getting the disease. Vaccination after 5 days may decrease risk of death due to smallpox, even if infection does occur.
8. Will a fit-tested N-95 mask on the caregiver completely protect against airborne spread?
Yes. A fit-tested N-95 mask is recommended by the CDC in their smallpox response plan. Respirators (N-95 or N-100) should be fit-tested each time they are worn to assure an adequate seal.
9. Is there any reason to place an N-95 mask on the patient?
Yes. Do this STAT when the patient is not in a negative pressure respiratory isolation room.
This is VERY IMPORTANT. The mask will decrease airborne spread.
10. If the patient is covered up, does that protect against spread of smallpox from the skin?
Yes. Anything that can minimize direct skin contact with the patient’s lesions, either by covering up the lesions or by Personal Protective Equipment (PPE) on the caregiver will decrease spread of the virus. Remember that appropriate patient care must still be provided despite whatever protection is taken to prevent smallpox transmission.
11. How contagious is smallpox?
Smallpox is less contagious than chickenpox or measles. With measles, the great majority of people in a large room will become infected if even only one person has measles. For smallpox the highest risk is to those who have face-to face contact with the patient (within 2 meters).
If there is personal protective equipment (fit-tested N-95 masks, gloves, etc.) on you and the patient, the risk of airborne spread becomes very low.
12. What exactly is the vaccine against smallpox?
The vaccine contains a live virus called “vaccinia”, which is very closely related to the smallpox virus (“variola”). Therefore, the vaccine cannot cause smallpox.
The vaccine is a weakened, or “attenuated” virus. Thus, it can cause significant vaccine adverse reactions, and rarely death, more so in persons with predisposing conditions (relative contraindications to vaccination - see the next question below).
Vaccination is given with a special “bifurcated” needle that is not difficult to learn how to use. The vaccine site (deltoid muscle) must be covered with two semipermeable membrane dressings (e.g., “Tegaderm”), gauze, & clothing to protect the live vaccinia virus from being transmitted to other persons-“contacts”.
In 2002 the smallpox vaccine will be offered on a VOLUNTARY basis. It will be given under FDA Investigational New Drug (IND) protocol only, and thus will require informed consent, close monitoring for side effects, and careful documentation.
13. What are the relative contraindications to vaccination (in the absence of exposure to smallpox, or in an epidemic situation when the risk/benefit ratio will change and these contraindications could change)?
Pregnancy.
Immunocompromised: steroids, transplants, cancer, HIV, others.
History of eczema (even if years ago and no longer active).
Active skin lesions including atopic dermatitis.
Household members with any of the above (1-4).
Allergy to tetracycline, polymyxin, neomycin, streptomycin (in vaccine).
14. What are the most severe risks of vaccination BOTH to “vaccinees” (i.e. the persons who receive the vaccine) and to their contacts?
The most complete nationwide vaccine safety data in the USA came from a national survey of all 50 states in 1968 (a subset of only 10 states were also surveyed in a different study in 1968 that used a different form of surveillance (more active) (for this data see Breman and Henderson NEJM April 25, 2002). The 50 state, nationwide survey found:
Deaths: 9 vaccinees died out of 14 million who received vaccine in 1968.
Other statistically rare, but severe adverse reactions to the vaccine included:
Encephalitis: 16 persons/14 million vaccinees (all 16: first-time vaccinees).
Progressive vaccinia--- necrosis of skin or muscle: 11 persons /14 million in 1968.
Eczema vaccinatum (can occur if a vaccinee or a contact of a vaccinee ever had a history of eczema): 66 vaccinees/14 million AND in another 60 persons with a history of eczema who were contacts of vaccines.
Generalized vaccinia: 141 vaccinees/14 million AND 2 contacts.
Note: Additional data on severe and mild (e.g., rash and lymphadenopathy) adverse effects of the vaccine can be found in the April 25, 2002 issue of the New England Journal of Medicine. Other good sources of information include the websites of the CDC (CDC.bt.gov) and the World Health Organization.
15. Are people who were vaccinated as children more protected than people who have never been vaccinated? (Note: the last routine vaccination in the USA was in 1972).
Adults in the USA are NOT protected against smallpox by a smallpox vaccination they received decades ago before 1972. Thus, they should be revaccinated if they are exposed to smallpox. People who have been vaccinated at least once probably do have a lower risk of death than persons never vaccinated; however, these persons are still at risk for being BOTH infected and infectious to other people if the time since their last vaccination is > 10 years.
16. Back when people were being vaccinated, how often were they receiving the vaccine?
Just once in the USA. Sometimes more often in endemic areas overseas.
The last cases of smallpox in the USA were in 1949 (Texas) and 1947 (NYC).
17. Do people who were vaccinated as children have less risk of complications from a current vaccination than people who have never been vaccinated?
Yes -- both in general, and specifically for encephalitis, eczema vaccinatum, and generalized vaccinia (1968 US data).
18. How bad a disease is smallpox and what is the expected mortality?
Bad. The average mortality rate has been 30% depending on when the last vaccination was given, the immune status of the person, and the particular clinical form (e.g., typical (30% mortality) vs. hemorrhagic or flat/malignant smallpox (>90% mortality).
In-hospital care of smallpox patients in 2002 may result in a lower mortality rate. This may be offset, however, by the larger number of immunocompromised people in the general population and the likely lack of enough hospital beds for a widespread epidemic.
19. Are there any FDA-licensed antiviral drugs for smallpox?
No. There are no antiviral drugs approved for the treatment of smallpox or for complications of smallpox vaccination. However, there is one antiviral drug “cidofovir” which might be studied on an “Investigational New Drug (IND)” basis under an FDA protocol. Cidofovir is currently FDA-approved only for treatment of CMV retinitis in persons with HIV/AIDS. Cidofovir is a toxic drug, particularly on the kidney. It can only be given IV and one dose lasts one week. Another medication, “probenecid” should always be given with cidofovir to decrease cidofovir’s nephrotoxicity.
20. If I am exposed to smallpox, must I get vaccinated before I go home to my family in order to prevent my spreading the disease to them?
No. You are not contagious for at least a week (i.e., the rash develops) and so as long as you get vaccinated within the first 2-3 days after exposure, your family should be safe from contracting smallpox from you.
21. If I am exposed to smallpox and receive the vaccination, should my family members be vaccinated also?
Yes, probably so, unless a family member has significant contraindication to vaccination.
22. Is there any treatment for complications of smallpox (vaccinia) vaccine?
Yes — Vaccinia Immune Globulin (VIG) is approved and has efficacy against certain of the more common serious vaccine reactions such as eczema vaccinatum and disseminated vaccinia.
However, VIG is not effective against vaccinia encephalitis, and is contraindicated in vaccinia keratitis (VIG may worsen the keratitis and loss of vision).
VIG only has efficacy against “vaccinia virus” (the virus contained in the vaccine). VIG has NO efficacy against actual smallpox disease (variola virus).
VIG is only given intramuscularly and requires large volumes (e.g., 42 ml for a
70 kg person [0.6 ml/kg]). Repeated doses may be needed.
VIG is in limited supply and is only available from the CDC under an FDA Investigation New Drug (IND) protocol.
23. What happens if I have a contraindication to vaccination and still get vaccinated against smallpox?
It depends on the contraindication. To take two examples:
If the contraindication is eczema, the risk is that you develop disfiguring disseminated skin lesions, termed “eczema vaccinatum”.
If the contraindication is HIV/AIDS, there is too little data to be sure about the probability and type of risk, since routine smallpox vaccination stopped in 1972 in the USA and the HIV epidemic was not recognized until 1981. However, there is a report of disseminated vaccinia in one military recruit with undiagnosed AIDS who received vaccination, and several reports of severe necrotic skin reactions in persons with HIV who were exposed to vaccinia virus. The military recruit recovered after multiple doses of Vaccinia Immune Globulin (VIG). Before 1972, immunocompromised patients were the ones most likely to develop “progressive vaccinia”, a rare and sometimes fatal reaction to the vaccine.
24. What do I do if I have a contraindication to vaccination, but have a definite exposure to smallpox?
Always a risk-benefit balance, but if you have a substantial exposure (e.g., face to face contact with known smallpox patient), then you probably should get the vaccine. Given face to-face exposure to smallpox, there is NO absolute contraindication to vaccination. VIG might be given along with the vaccine to lessen the risk of severe vaccine reactions, if VIG is available.
25. What is the procedure for definitive diagnosis of a patient suspected of smallpox?
The Department of Health is informed STAT. A sample of a skin lesion is flown to the CDC in Atlanta for testing. It takes about 8-24 hours for CDC to confirm or exclude the diagnosis of smallpox. No vaccine will be released until confirmation of smallpox is made.
26. Why shouldn’t I just “run for the hills” if smallpox is found?
The best defense against smallpox is getting vaccinated. Healthcare workers at a hospital containing a possible smallpox patient will almost certainly have a priority for receiving smallpox vaccine. In addition, travel restriction will likely be enforced early during a smallpox outbreak.
Remember and remind everyone: Being in the hospital where a possible patient with smallpox is being cared for ensures the highest probability of being vaccinated yourself and thus being protected against getting smallpox.
Being at work at a hospital also provides the highest likelihood of treatment with Vaccinia Immune Globulin (VIG) if it is needed to help manage a severe vaccine reaction. Act with courage, as during the time of anthrax in 2001.
27. How do you disinfect a room after it has had a patient with smallpox?
All clothing and sheets must be considered infectious and kept in the room until they can be properly bagged and removed to be autoclaved. All surfaces should be cleaned with a freshly prepared solution of 1:10 bleach: water solution. A protocol with specific recommendations is from the Infection Control office at most hospitals.
28. Who should be called if I suspect a person might have smallpox?
At most hospitals the following persons should be notified STAT:
-Emergency Department Administrator
-Hospital Administrator on call
-Infection Control Practitioner
-Department of Health
-Infectious Disease Service
-Nursing Supervisor on call
-Facilities Engineer on call (to control airflow to minimize virus spread)
-Protective Services (security)
29. 3 Key points:
1. Place an N-95 respiratory mask on yourself and the patient
2. Notify appropriate people STAT (see above)
3. Track all patients and healthcare workers who may be exposed so they can
be vaccinated in order to be protected against smallpox.
This FAQ Prepared By:
Daniel Lucey, MD
Director, Center for Biologic Counterterrorism and Emerging Disease
Mark Smith, MD
Chairman, Department of Emergency Medicine
Washington Hospital Center
Christopher Wuerker, MD
Chair, Emergency Management Committee
Washington Hospital Center
Nancy Donegan, RN
Infection Control Service
Washington Hospital Center