ARCHIVED - Smallpox vaccination of laboratory workers


In accordance with a statement from the National Advisory Committee on Immunization on smallpox vaccine, Health Canada provides smallpox vaccine to laboratory staff who work with vaccinia or other orthopoxviruses(1). Potential candidates for the vaccine are identified by the laboratory and, if they wish to receive the vaccine, they are screened for medical contraindications that include atopic dermatitis, immunodeficiencies or pregnancy in either the potential vaccinee or a close contact; or cardiac disease, the presence of three or more cardiac risk factors, breastfeeding, the use of steroid eye drops or allergy to vaccine components in the potential vaccinee(2, 3).

Since September 2003, a self-administered pre-vaccination survey was completed by 25 laboratory workers from three laboratories. The median age of these individuals was 34 years (range 20-57 years) and 13 (52%) were male. Twelve (48%) indicated that they had been vaccinated in the past, 11 (44%) had not, and 2 (8%) did not know.

Ten (40%) workers indicated that they would like to be vaccinated or revaccinated against smallpox. Nine (36%) individuals were ineligible for the vaccine due to medical contraindications in themselves (4 persons), household contacts (4) or both (1). One previously vaccinated individual had both cardiac risk factors and was using steroid eye drops while four unvaccinated workers had a history of eczema. Among household contacts of previously vaccinated persons, one was immunocompromised and one had a serious skin condition other than eczema. Among household contacts of unvaccinated individuals, two had a history of eczema and one was pregnant. Table 1 summarizes the characteristics of these 25 labratory workers.

Four labratory workers have been vaccinated to date using the Canadian-licensed, lyophilized vaccine, a New York City Board of Health strain of vaccinia manufactured in the 1970s. The median age of the workers was 30 years (range 23-44 years), two were male and three had previously been vaccinated. One worker, who was vaccine-experienced, did not exhibit a take reaction after 1 week and therefore required revaccination. No serious adverse events were reported. One worker developed a viral cellulitis that resolved on its own.

For more information on obtaining smallpox vaccine for laboratory workers, please contact the Office of Public Health Security, Health Canada at 613 954 8498.

Table 1. Characteristics of laboratory workers with and without previous vaccination against smallpox

Mean age

Previous vaccination (n=12)

No or unknown previous vaccination (n=13)


44 years
(range 22-57 years)

29 years
(range 20-47 years)

< 0.05


7 (58%)

6 (46%)




Computer programmer
Graduate student
Not specified

3 (25%)
7 (58%)
2 (17%)

6 (46%)
2 (15%)
1 (8%)
2 (15%)
2 (15%)


Do not want or do not know if they want to receive vaccine now

5 (42%)

10 (77%)


Reasons for not wanting vaccine now (participants may have given more than one response)


Concerned about adverse events
Vaccine not necessary for work
Medical contraindication
Medical contraindication in a household contact

2 (40%)
1 (20%)
1 (20%)
2 (40%)

6 (60%)
2 (20%)
4 (40%)
3 (30%)



  1. National Advisory Committee on Immunization. Statement on smallpox vaccination. CCDR 2002;28:1-12.

  2. Centers for Disease Control and Prevention. Recommendations for using smallpox vaccine in a pre-event vaccination program. MMWR 2003;52:1-16.

  3. Centers for Disease Control and Prevention. Supplemental recommendations on adverse events following smallpox vaccine in the pre-event vaccination program: Recommendations of the Advisory Committee on Immunization Practices. MMWR 2003;52:282-84.

Source: Centre for Emergency Preparedness and Response, Population and Public Health Branch, Health Canada.

Report a problem or mistake on this page
Please select all that apply:

Thank you for your help!

You will not receive a reply. For enquiries, contact us.

Date modified: