Varicella Outbreak Among Recent Arrivals to New York City, 2022–2024

Varicella is an illness characterized by a generalized, pruritic rash and transmitted through airborne, droplet, and contact transmission.Although varicella causes mild-to-moderate symptoms in most persons, serious complications, including pneumonia and death, can occur.In October 2022, the New York City (NYC) Department of Health and Mental Hygiene (DOHMH) identified a varicella outbreak primarily involving persons who recently migrated from or through Central and South America and lived in an NYC shelter or residential facility; the outbreak is ongoing.Persons with suspected varicella were reported to DOHMH by city-run shelters and residential facilities, schools, and health care facilities.DOHMH investigations included patient interview and review of medical and immunization records.As of March 8, 2024, a total of 873 outbreak-associated varicella cases were reported.An outbreakassociated case was defined as a clinically compatible rash and either provider diagnosis of or known exposure to varicella in a person who recently had migrated from or through Central or South America or had an epidemiologic link to someone who did.The majority of cases (53.0%) were among children and adolescents aged 4-18 years, and most patients (91.9%) had no documentation of varicella vaccination at the time of symptom onset.In total, 28 varicella-associated hospitalizations and no deaths to date were reported.Among 780 (89.3%) cases with a known source of transmission, the most common sources included shelters and residential facilities (41.3%) and importation or possible importation (39.4%).School transmission accounted for only 1.2% of cases.Ongoing control measures include isolation of infectious persons, quarantine of nonimmune contacts, recommended temporary closure of shelters and residential facilities with evidence of residence-based transmission, and providing or supporting varicella vaccination operations.Approximately 27,000 varicella-containing vaccine doses have been administered to recently arrived migrant children, adolescents, and adults by vaccination vendors deployed by DOHMH and NYC's public hospital system.This outbreak highlights the importance of limiting transmission by achieving and maintaining high varicella vaccination coverage and the need for rapid, large-scale vaccination efforts given ongoing importations and exposures in shelters and residential facilities. Investigation and Findings Identification of Varicella OutbreakVaricella is an illness characterized by a generalized, pruritic rash and transmitted through airborne, droplet, and contact transmission.Although varicella causes mild-to-moderate symptoms in most people, serious complications, including pneumonia and death, can occur.Varicella vaccine is highly Morbidity and Mortality Weekly Report