Control of Varicella Outbreak among Healthcare Workers in Intensive Care Unit in Saudi Arabia

Objectives: To investigate the epidemiology of a hospital-acquired varicella outbreak and to assess the effectiveness of infection control measures. Methods: From December 2024 to March 2025, a retrospective analysis of an outbreak occurred in the ICU of the Ministry of Health's tertiary care hospital. Cases were diagnosed using clinical and serological characteristics consistent with chickenpox. An epidemiological investigation included developing case definitions, line listing, spot mapping, and contact tracing. Results: The index case was a 49-year-old male patient who had been referred from another facility. He was admitted to the ICU upon arrival at the hospital. One day later, a skin biopsy revealed that the patient was infected with the chickenpox virus. The Primary case was later diagnosed as varicella based on clinical and serological evidence. The infected cases had a mean age of 31.5 ± 7.83 years, with 70.6 % female and 35.3 % Saudi Arabian. There were two physicians (11.8%), fourteen nurses (82.4%), and one patient (5.9%). All the reported cases had not previously received the varicella vaccine (64.7%) or had invalid vaccination data (35.3%). The epidemiological investigation revealed a total of 160 susceptible contacts. Susceptible individuals received two doses of the varicella vaccine. Conclusion: A significant number of healthcare workers in the ICU were involved in the outbreak. Serological testing and subsequent vaccination for non-immune healthcare workers should be documented. Triage, immediate isolation of suspected or confirmed cases, post-exposure prophylaxis for non-immune exposed individuals, reinforcement of airborne and contact precautions, and temporary exclusion of at-risk non-immune staff from patient care are all highly recommended. Regular training for HCWs on infection control measures, epidemiology of airborne diseases, and outbreak preparedness is mandatory.