Assessing Immunity to Varicella (Chicken Pox)

Within the new Chapter 264: IMMUNIZATION REQUIREMENTS FOR HEALTHCARE WORKERS the Maine Department of Health and Human Services prescribes the dosage for required immunizations and defines responsibilities, exclusion periods, record keeping and reporting requirements for officials of hospitals and healthcare facilities. Except as otherwise provided by law, each Designated Healthcare Facility in the State of Maine must require for all employees proof of immunization or documented immunity against the following MMR, Varicella, Hep B, Influenza and COVID-19.

Member homes have submitted questions to MHCA regarding the previous practice of accepting an employees self-identified immunity to Varicella or chicken pox based on childhood infection as an acceptable means of documenting immunity. This is NO LONGER an acceptable means of documentation. Below is information related to the Varicella vaccine and evidence of immunity as it relates to our healthcare workforce.

According to the
CDC's Varicella Vaccine Recommendations:

Two doses of varicella vaccine are recommended for all children, adolescents, and adults without evidence of immunity to varicella. Those who previously received one dose of varicella vaccine should receive their second dose for best protection against the disease.
Evidence of immunity to varicella includes any of the following:
  • Documentation of age-appropriate varicella vaccination
  • Laboratory evidence of immunity or laboratory confirmation of disease*
  • Birth in the United States before 1980 (should not be considered evidence of immunity for healthcare personnel, pregnant women, and immunocompromised people)
  • Diagnosis or verification of a history of varicella or herpes zoster by a healthcare provider
*Commercial assays can be used to assess disease-induced immunity, but they lack sensitivity to detect vaccine-induced immunity (i.e., they might yield false-negative results).

To verify a history of varicella, healthcare providers should inquire about:
  • An epidemiologic link to another typical varicella case or to a laboratory confirmed case, or
  • Evidence of laboratory confirmation, if testing was performed at the time of acute disease
  • People who have neither an epidemiologic link nor laboratory confirmation of varicella should not be considered as having a valid history of disease. For these people, a second dose of vaccine is recommended if they previously received only one dose. If a healthcare provider verifies the diagnosis based on the above criteria, then vaccination is not needed.
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