Varicella cluster in Tukwila, King County

Actions requested

• Be aware of at least two laboratory-confirmed varicella (chickenpox) cases among asylum seekers who have been staying in a homeless encampment in Tukwila.
• Secondary cases would be expected between December 3, 2023, to December 23, 2023.
• Assess immunity status of patients at every visit and vaccinate based on the CDC recommended schedule, health condition, occupation, and other risk factors such as travel. Under-vaccinated individuals may be at risk for varicella infection. Document vaccinations administered in the Washington State Immunization Information System.
• Consider varicella infection in exposed patients with compatible symptoms:
• A mild prodrome of fever, up to 102°F, and malaise may occur 1-2 days prior to rash onset
• Pruritic rash that starts on the chest, back and face, spreads over entire body, and progresses rapidly from macular to papular to vesicular lesions before crusting over
• In vaccinated people who later develop infection, disease is milder with fewer than 50 skin lesions and shorter duration of illness, rash may be atypical (maculopapular with few or no vesicles)
• Complications from varicella include bacterial infections of skin and soft tissue and pneumonia. Severe complications include cerebellar ataxia, encephalitis, viral pneumonia, and hemorrhagic conditions. More moderate to severe disease is likely to occur in:
• Pregnant people without evidence of immunity
• Immunocompromised people without evidence of immunity
• Infants, especially those who are:
• Newborns whose mother had varicella infection from 5 days before to 2 days after delivery
• Premature babies exposed to varicella or herpes zoster
• Healthy adolescents over age 12 years and adults without evidence of immunity
• Consider oral acyclovir or valacyclovir for treatment within 24 hours of rash onset in people at increased risk for moderate to severe disease.
• Intravenous acyclovir is recommended for treatment of severe disease and for varicella in immunocompromised people
• Offer preventative measures to all exposures:
• Varicella vaccination for all exposures without evidence of immunity or contraindications, and preferably within 3 days but up to 5 days after exposure, to prevent or modify disease
• Pregnancy is a common contraindication to varicella vaccine
• Varicella-zoster immune globulin (VariZIG) is recommended for people who cannot receive the vaccine and:
• lack evidence of immunity of varicella,
• whose exposure is likely to result in infection, and
• are at highest risk for severe varicella per ACIP guidelines

VariZIG should be given as soon as possible and within 10 days of exposure. For patients who received VariZIG, administration of subsequent varicella vaccines should be delayed until 5 months after VariZIG is administered.

• For situations where VariZIG is recommended but not available, an infectious disease consult or discussion with Public Health is advised.
• Be prepared for infection prevention measures at your facility:
• Airborne and contact precautions for all patients with suspected infection
• Screen patients for symptoms and exposure at triage or appointment scheduling for rapid identification and implementation of appropriate precautions
• Suspected patients should be cared for by non-pregnant healthcare workers who have evidence of immunity to varicella