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Varicella zoster virus (VZV) causes two distinct diseases: chickenpox and “shingles” (herpes zoster). Acute chickenpox is highly contagious and usually runs its course in about a week or two, producing immunity, but VZV is not eliminated from the body. The virus becomes dormant in the sensory ganglia and may reactivate decades later to produce zoster [58]. To decrease the incidence of chickenpox in adults who were never exposed to VZV as a child, routine childhood vaccination began in 1995. The full vaccine regimen (two doses) is 90‐100% protective against chickenpox, and virtually 100% effective against severe disease [58]. Serologic screening for VZV immunoglobulin G is indicated for adult health care workers who do not have a documented history of chickenpox. VZV is common, so ensuring EMS clinicians are immune prior to patient care is important and cost effective. Only immune health care personnel should care for patients with chickenpox or shingles. If a pregnant EMS clinician has a documented history of chickenpox or has positive titers, she is considered to be immune and can care for patients. Both she and the fetus are protected.

Nonimmune adults exposed to either chickenpox or zoster can develop acute chickenpox, including potential complications of pneumonia, encephalitis, and death. Nonimmune personnel exposed to chicken pox or disseminated zoster must avoid patient contact from 10 days after the exposure (the incubation period) until day 21 [58]. An exposure is defined as a breach of contact precautions (such as localized direct contact with uncovered lesions) and/or breach of airborne precautions (chickenpox or disseminated zoster).

If an unprotected exposure occurs to a nonimmune health care professional, unless that person is pregnant or immunocompromised, the vaccine should be given within 3‐5 days. For people exposed to VZV who are nonimmune or cannot receive the varicella vaccine, varicella zoster immune globulin can prevent varicella from developing or lessen the severity of the disease. It should be given as soon as possible after exposure. Oral acyclovir or valacyclovir treatment should be considered in certain groups at increased risk for moderate to severe illness. These high‐risk groups include healthy people older than 12 years, people with chronic cutaneous or pulmonary disorders, people receiving long‐term salicylate therapy, and people receiving short, intermittent, or aerosolized courses of corticosteroids. Some physicians may elect to use oral acyclovir or valacyclovir for secondary cases within a household. Oral therapy should be given within the first 24 hours after the varicella rash starts, but is not recommended for use in otherwise healthy children experiencing typical varicella without complications.