What are the recommendations for managing norovirus infections?

Norovirus Management Recommendations

The most effective management of norovirus infections requires proper hand hygiene with soap and running water for at least 20 seconds, isolation of infected individuals for 48-72 hours after symptom resolution, and thorough environmental disinfection with chlorine bleach solutions (1,000-5,000 ppm) or EPA-approved disinfectants. 1

Prevention and Control Measures

Hand Hygiene

• Proper handwashing with soap and running water for at least 20 seconds is the single most important method to prevent norovirus infection and control transmission 1
• Alcohol-based hand sanitizers (≥70% ethanol) can be used as an adjunct between proper handwashings but should not be considered a substitute for soap and water handwashing 1
• No bare-hand contact with ready-to-eat foods is recommended as an additional preventive strategy 1

Exclusion and Isolation

• Exclude ill staff in certain positions (e.g., food handlers, child-care, and patient-care workers) until 48–72 hours after symptom resolution 1
• In closed or institutional settings (e.g., long-term-care facilities, hospitals, and cruise ships), isolate ill residents, patients, and passengers until 24–48 hours after symptom resolution 1
• In healthcare facilities, ill patients may be cohorted together in a unit with dedicated nursing staff providing care for infected persons 1
• Ill patients generally should not be transferred to unaffected units or other facilities except in cases of medical necessity 1

Environmental Disinfection

• After initial cleaning to remove soiling, disinfect potentially contaminated environmental surfaces using a chlorine bleach solution with a concentration of 1,000–5,000 ppm (1:50–1:10 dilution of household bleach [5.25%]) or other EPA-approved disinfectant 1
• Pay particular attention to bathrooms and high-touch surfaces (e.g., door knobs and hand rails) 1, 2
• In healthcare settings, cleaning products and disinfectants used should be EPA-registered and have label claims for use in healthcare 1
• Personnel performing environmental services should adhere to the manufacturer's instructions for dilution, application, and contact time 1

Outbreak Management

Investigation and Reporting

• Initiate investigations promptly, including collection of clinical and epidemiologic information, to help identify predominant mode of transmission and possible source 1
• Collect whole stool specimens from at least five persons during the acute phase of illness (≤72 hours from onset) for diagnosis by RT-qPCR 1
• Report all outbreaks of acute gastroenteritis to state and local health departments, in accordance with local regulations, and to CDC via the National Outbreak Reporting System (NORS) 1

Foodborne Outbreak Considerations

• Restaurants are the most common setting (64%) of food preparation reported in outbreaks 3
• Food workers are implicated as the source in 70% of outbreaks with identified contributing factors 3
• Most outbreaks result from food contaminated during preparation (92%) and food consumed raw (75%) 3
• The most frequently implicated food categories include vegetable row crops (e.g., leafy vegetables), fruits, and mollusks 3

Special Considerations for Healthcare Settings

• Isolation of both exposed and unexposed well persons might be useful during outbreaks in long-term-care facilities to help break the cycle of transmission 1
• To minimize risk of spread from incubating or asymptomatically infected patients and staff, such persons should not be transferred to or work on unaffected areas, typically for 48 hours after exposure 1
• In certain situations, units in a healthcare facility may be closed to new admissions to prevent the introduction of new susceptible patients 1, 4
• Sick pay and sick leave policies that do not penalize ill workers might help facilitate staff exclusion 1

Common Pitfalls and Caveats

• Requiring negative stool results prior to returning to work is not recommended 1
• Alcohol-based hand sanitizers have limited efficacy against norovirus and should not replace proper handwashing with soap and water 1
• Evidence for efficacy against norovirus is often based on studies using feline calicivirus (FCV) as a surrogate, but FCV and norovirus exhibit different physiochemical properties 1
• Even with enhanced hygiene measures, complete containment of norovirus outbreaks is challenging due to the virus's high infectivity, environmental stability, and low infectious dose 2, 5, 6