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Vaccines and Preventable Diseases:

Varicella Vaccine -
Q&As about Healthcare Providers
Clinical Questions and Answers

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Does ACIP recommend varicella vaccination of healthcare providers (HCPs)?

ACIP, with support by the Hospital Infection Control Practices Advisory Committee (HICPAC), recommends that healthcare institutions ensure that all healthcare providers have evidence of immunity to varicella. For healthcare providers, evidence of immunity includes any of the following:

  • Documentation of two doses of varicella vaccine;
  • Blood tests showing immunity to varicella or laboratory confirmation of prior disease; or
  • Receipt from a healthcare provider of a) a diagnosis of chickenpox or herpes zoster (shingles); or b) verification of a history of chickenpox or herpes zoster (shingles).

Birth before 1980 is not considered evidence of immunity for HCPs because of the potential for nosocomial transmission of varicella to high-risk patients.

Healthcare institutions should establish protocols and recommendations for screening and vaccinating HCPs and for management of HCPs after exposure in the workplace.

Should HCPs be tested for varicella zoster virus (VZV) immunity prior to vaccination?

Serologic screening before vaccination of personnel who have negative or uncertain history of varicella disease is likely to be cost effective. Most adults (70-90%) who do not remember having chickenpox actually have protection in their blood when tested. Institutions may elect to test all HCPs regardless of disease history because a small proportion of persons with a positive history of disease might be susceptible. The tests most widely used to detect varicella IgG antibody after natural varicella infection among HCPs are latex agglutination (LA) and ELISA. Although the LA test is generally more sensitive than commercial ELISAs, a recent report indicated that the LA test can produce false-positive results, particularly when only a single concentration of serum is evaluated. Therefore, for the purpose of screening HCPs for varicella susceptibility, a less sensitive and more specific commercial ELISA should be considered.

Should HCPs be tested after vaccination to ensure that they are immune?

The ACIP and HICPAC do not recommend routine testing of HCPs for varicella immunity after two doses of vaccine. Available commercial assays are not sensitive enough to detect antibody after vaccination in all instances. Sensitive tests have indicated that 99% of adults develop antibodies after the second dose. However, seroconversion does not always result in full protection against disease, and no data regarding correlates of protection are available for adults. See also How should vaccinated HCPs be managed after exposure to natural varicella? .

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Are recently vaccinated HCPs at risk for transmitting vaccine virus to susceptible persons?

The risk of transmission of vaccine virus from persons who develop a varicella-like rash after vaccination is low, and has been documented only after exposures in households and long term care facilities.No cases have been documented after vaccination of HCPs. Moreover, the benefits of vaccinating HCPs who do not have evidence of immunity outweigh this extremely low potential risk. As a safeguard, precautions should be taken for personnel who develop rash after vaccination. These individuals should avoid contact with persons without evidence of immunity who are at risk for severe disease and complications until all lesions resolve (i.e., crusted over or fade away) or no new lesions appear within a period of 24 hours.

How should vaccinated HCPs be managed after exposure to natural varicella?

Exposed HCPs who have received 2 doses of vaccine should be monitored daily during days 10-21 after exposure through the employee health program or by an infection control nurse to determine clinical status (i.e., daily screening for fever, skin lesions, and systemic symptoms). They should also be instructed to report any symptoms as they occur without delay. If symptomatic, HCPs should be placed on sick leave immediately. Exposed HCPs who have received 1 dose of vaccine and who are exposed to VZV should receive the second dose of vaccine within 3-5 days post exposure to rash (provided 4 weeks have elapsed after the first dose). After vaccination, management is similar to that of 2-dose vaccine recipients described above.

What is recommended for unvaccinated HCPs without evidence of immunity (Can you link this to the first question?) who are exposed to natural varicella?

Unvaccinated HCPs who have no evidence of immunity and are exposed to natural varicella are potentially infective from days 10-21 after exposure and should be furloughed during this period. Postexposure vaccination is recommended within 3-5 days of exposure to rash, since it may attenuate the disease substantially if infection occurred. If the exposure did not cause infection, vaccination more than 5 days after exposure is still indicated as it induces protection against subsequent infection.

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This page last modified on June 12, 2007
Content last reviewed on June 12, 2007
Content Source: National Center for Immunization and Respiratory Diseases

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