QAPI 113 - A Comprehensive Infection Control Response to a Norovirus Outbreak on an Adult Inpatient Hematologic Oncology and Clinical Trials Unit

Background: In December 2022, an increase in patient norovirus cases was detected on an adult inpatient hematologic oncology and clinical trials unit at a tertiary oncology hospital. Concurrent gastrointestinal symptoms in staff with epidemiological links to patient cases prompted an investigation and implementation of infection control measures.

Methods: Infection Prevention and Control (IPC) held multidisciplinary meetings with stakeholders to implement control measures in a systematic manner as more cases were identified. The patient-focused response included universal contact precautions, quarantine of exposed roommates, point prevalence unit-wide testing, surveillance of gastrointestinal symptoms for newly admitted patients, and restriction of unit admissions and transfers. Environmental measures involved unit-wide bleach cleaning and restriction of pantry access. The employee response included daily staff screening for symptoms, coordination of testing of symptomatic employees when feasible, return-to-work clearance requirement for all sick staff, prohibition of cross coverage to other units, and ultimately, cohorting staff to affected patients. IPC increased unit rounding to ensure mitigation measures were followed.

Results: Between December 20 and 31, 2022, there were 11 confirmed patient cases and 19 employee cases with concurrent gastrointestinal symptoms and/or confirmed norovirus (n=3) included in this outbreak. Additionally, two probable patient cases were identified but not included in the case count due to lack of confirmatory testing. In total, 13 patients were quarantined, of whom one tested positive and two were probable cases. Three additional patients had negative tests without quarantine following exposure to sick staff. Following one full week of no new cases attributed to the unit, response measures were discontinued with no recurrence.

Conclusions: Norovirus poses a high risk to oncology patients and transmission occurs rapidly between patients and staff. Reduction measures such as patient quarantine, increased personal protective equipment, bleach cleaning and disinfection, staff cohorting, syndromic surveillance, and surveillance testing should be considered as interventions for high-risk patient populations.