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Vaccinia Virus Use & Immunization Policy for Laboratory Personnel

Introduction

Recombinant vaccinia and other pox viruses are useful microbiological research tools for expression of exogenous proteins in a variety of cultured cell types. However, their use is not without risk to laboratory personnel. As stated in the Centers for Disease Control and Prevention and National Institutes of Health's Biosafety in Microbiological and Biomedical Laboratories1 :

  • Naturally or experimentally infected laboratory animals are a potential source of infection to exposed unvaccinated laboratory personnel.
  • Genetically engineered recombinant vaccinia viruses pose an additional potential risk to laboratory personnel, through direct contact or contact with clinical materials from infected volunteers or animals.
  • The agents may be present in lesion fluids or crusts, respiratory secretions, or tissues of infected hosts.
  • Ingestion, parenteral inoculation, and droplet or aerosol exposure of mucous membranes or broken skin with infectious fluids or tissues, are the primary hazards to laboratory and animal care personnel.
  • All manipulations of vaccinia strains BSL-2 and above should be conducted in a biosafety cabinet. When work must be performed outside of a biosafety cabinet (e.g. animal surgery, microscopy), the following personal protective equipment must be used:
    • gloves
    • lab coat
    • eye and mucous membrane protection [safety glasses or goggles which are ANSI certified and surgical mask or face shield]. Serious ocular infections can occur even in vaccinated individuals. 2, 3

Multiple strains of vaccinia virus exist with varying levels of virulence for humans and animals. Depending on the strain used, vaccinia virus presents varying levels of health risk to laboratory personnel. Strains that are highly attenuated are typically unable to replicate or replicate poorly in human cells. On the other hand, nonhighly attenuated strains of vaccinia have the ability to replicate in human cells and thus pose a risk to humans. Risks include localized skin infections and more severe, disseminated reactions to which immunocompromized individuals may be more susceptible.

The following information is based on national guidelines issued by the CDC in Vaccinia (Smallpox) Vaccine Recommendations of the Advisory Committee on Immunization Practices2 .

Vaccination is not recommended for those working with the following highly attenuated strains (see chart below):

Highly Attenuated StrainBiosafety
Level *		Derived from:
MVA 2Vaccinia virus (Ankara)
NYVAC 1Vaccinia virus (Copenhagen)
TROVAC 1Fowlpox virus
ALVAC 1Canarypox virus

* Biosafety level may increase depending on the presence and characteristics of a foreign protein expressed by a recombinant vaccinia virus or other aspects of the proposed experiment.

  • Laboratory personnel who work with highly attenuated strains of vaccinia virus (e.g., MVA and NYVAC) or who work with the Avipoxvirus strains ALVAC and TROVAC do not require routine vaccinia vaccination.
  • The Occupational Safety Health Board of NIH no longer requires vaccinia vaccination for personnel manipulating MVA or NYVAC in laboratories using only those strains.
  • The Recombinant DNA Advisory Committee of the NIH reduced the biosafety level of NYVAC, TROVAC and ALVAC to level 1 based on accumulated attenuation data and biological properties of these strains.
  • Although there is no formal surveillance system in place, there have not been any reports of laboratory-acquired infection resulting from exposure to any of the above highly attenuated strains or recombinant vaccines derived from these strains in the literature or to the CDC.
  • Appropriate biosafety guidelines and infection control procedures should always be observed when working with viral material even if vaccination is not indicated.

Vaccinia vaccination is recommended (but not required)4 for laboratory workers who directly handle a) cultures or b) animals infected with:

  • nonhighly attenuated vaccinia virus strains
  • recombinant vaccinia viruses derived from nonhighly attenuated vaccinia strains
  • other orthopox viruses that can infect humans

Nonhighly attenuated strainsWR (Western Reserve, mouse neuroadapted derivative)
NYCBOH (strain used in vaccinia vaccine)
Copenhagen
Temple of Heaven
Lister
Other orthopox virusesCowpox, Monkeypox

  • The vaccine, Dryvax®, is a live virus preparation of vaccinia virus manufactured by Wyeth and distributed by the CDC. It is administered with a bifurcated needle using a multi-puncture technique.
  • Vaccinia immunization results in high seroconversion. The resulting immunity should provide protection to recipients against infections resulting from uncontrolled, inadvertent inoculation by unusual routes (e.g., the eye) with a substantial dose of virus of higher or unknown pathogenicity.
  • Individuals with certain conditions are more likely to experience severe side effects or complications from the vaccine and should not be vaccinated. Contraindications include eczema, atopic dermatitis, immunosuppression and pregnancy, or having household contacts with any of these conditions.
  • Revaccination every 10 years is recommended for people working with nonhighly attenuated vaccinia strains; more frequent revaccination may be required for more virulent orthopox viruses.
  • Laboratory personnel not directly handling cultures of vaccinia or animals infected with vaccinia, but working in the same lab where nonhighly attenuated strains are being used should be offered medical screening for potential contraindications to vaccinia exposure.
  • Other health-care workers (such as physicians and nurses) whose contact with these viruses is limited to contaminated materials (for example, dressings), but who adhere to appropriate infection control measures, are probably at lower risk for inadvertent infection than laboratory workers. However, because a theoretical risk of infection exists, vaccination may be considered for this group.
  • A summary of published case reports of laboratory-acquired vaccinia virus infections is available in the Journal of the American Biological Safety Committee, Applied Biosafety, 10(2) 2005, p.118-122 by Karen Byers.

Policy Statement

In the interest of providing a safe workplace and to comply with federal regulations, the Institutional Biosafety Committee (IBC) has formulated a policy regarding immunization for workers in laboratories using vaccinia and other pox viruses. Recommendations for vaccination will be dependent upon on the strain used in the proposed research. The IBC policy follows national guidelines set forth by the CDC as described above.

Based on these guidelines, laboratory personnel for whom vaccination is recommended must receive mandatory confidential medical counseling before beginning work with the virus. These individuals must be counseled on the risks and benefits of the vaccine and medically screened for contraindications to vaccinia exposure or vaccination.

Instructions to Principal Investigators for obtaining IBC approval to use vaccinia virus and receive vaccination

  1. Principal Investigators must register research involving vaccinia virus work with the IBC. (see "Inventory and Activity Registration")
  2. PIs who have proposed research activities where vaccination is recommended must also complete the CDC form "Request for Vaccinia (Smallpox) Vaccine" (.doc or .pdf).
    1. Complete the section entitled "Head of Laboratory doing research with virus(es)."
    2. List the individuals in the lab who work directly with vaccinia virus (Name, Age, Position-Duties). The list should include only those who directly handle vaccinia cultures or animals contaminated or infected with vaccinia, recombinant vaccinia, or other orthopox viruses. List all individuals who fall into the category of having direct contact, even if you are aware that they may not be interested in receiving the vaccine. This is to ensure completeness of records of who is working with vaccinia and who needs confidential counseling.
  3. Send the completed form to UVA WorkMed via mail or fax. WorkMed (opens a new browser window) will complete the top portion of the form and forward it to the CDC.

    545 Ray C. Hunt Drive - Fontaine Research Park
    P.O.Box 800357
    Suite 3200 3rd Floor Musculoskeletal Center
    Charlottesville, VA 22903
    ph: 434-243-0075
    f: 434-243-0078
  4. After the Vaccine Request Form is sent to WorkMed (opens a new browser window), each person listed on the form must contact WorkMed and schedule a mandatory confidential counseling visit before beginning work with vaccinia. During the counseling session, the risks and benefits of vaccinia immunization will be discussed and concerns or questions will be addressed.

Following medical consultation the individual will either:

  1. sign a vaccinia vaccination consent form and receive the vaccine. (This will require follow-up visits to monitor the vaccination site), OR
  2. sign a declination form, OR
  3. if WorkMed determines that vaccination is contraindicated, the PI will be contacted by WorkMed and alterations in the individual's lab duties and responsibilities may be made in order to protect the health and safety of that person.
  1. IBC approval may occur before all personnel listed on the Request for Vaccinia Vaccination form has been counseled and vaccinated. It is the Principal Investigator's responsibility to ensure that all personnel working directly with vaccinia have received counseling. Evidence of medical counseling must be documented in the laboratory biosafety manual.

CDC Links:
Smallpox Fact Sheet (opens a new browser window)
Smallpox Vaccine: What You Need to Know (opens a new browser window)

1 Centers for Disease Control and Prevention and National Institutes of Health. Biosafety in Microbiological and Biomedical Laboratories. 4th ed. Atlanta, GA, US Department of Health and Human Services, 1999.
2 Lewis et al. Ocular vaccinia infection in a laboratory worker, Philadelphia, 2004. Emerging Infectious Diseases. 12(1) 2006: 134-7.
3 Ruben FL & Lane JM. Ocular Vaccinia. Archives of Ophthalmology 84, 1970: 45-48.
4 Centers for Disease Control and Prevention. Vaccinia (smallpox) vaccine recommendations of the advisory committee on immunization practices. (ACIP). MMWR, Recommendations and Reports, 50, 2001.