Varicella cluster in Tukwila, King County

Actions requested

• Be aware of at least 3 clinically diagnosed varicella (chickenpox) cases among asylum seekers who have been staying in a homeless encampment in Tukwila.
• Secondary cases would be expected through the end of June 2024.  
• Assess immunity status of patients at every visit and vaccinate based on the CDC recommended schedule, health condition, occupation, homelessness, and other risk factors such as travel. Under-vaccinated individuals may be at risk for varicella infection.
• Important - Document historical and administered vaccinations and serology (IgG and IgM results) in the Washington State Immunization Information System.
• Consider varicella infection in exposed patients with compatible symptoms or complications and perform laboratory testing to verify diagnosis.
• 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 one of these recommended preventative measures to all eligible people who are exposed:
• 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) for people who cannot receive the vaccine and:
• lack evidence of immunity to 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/known 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
• Assess pregnant persons for evidence of immunity and consider varicella IgG serology if there is no evidence of immunity, especially for persons experiencing homelessness or asylum seekers.
• Report suspected cases of varicella among asylum seekers, people experiencing homelessness, and anyone with close contact to these populations to Public Health at (206) 296-4774 within 24 hours.