Public Health Agency



Noroviruses are non-enveloped viruses that belong to the Caliciviridae group of viruses and are a frequent cause of infectious gastroenteritis. The group was previously known as ‘Small Round Structured Virus’ or SRSV. Norovirus may cause vomiting, diarrhoea, nausea and abdominal cramping and is usually spread by the faecal-oral route. Vomiting causes widespread contamination of the environment leading to indirect person-person spread. Outbreaks are common in environments such as hospitals, nursing homes, schools and cruise ships. People of all ages are at risk of developing norovirus. Norovirus infections in a hospital/Care Home can be very disruptive, as wards/sections of the care home may need to be closed to new admissions in order to prevent the spread of infection.

What are the symptoms?

Symptoms of infection generally last for approximately 12-48 hours and may include:

  • abdominal cramps
  • sudden onset of forceful vomiting – often projectile vomiting
  • diarrhoea/loose bowel motions
  • headache
  • raised temperature/feeling flushed
  • myalgia/general tiredness and feeling ‘unwell’

How does norovirus spread?

Humans are the only known carriers of norovirus. It cannot be caught from animals, although some food, e.g. shellfish, may be contaminated. Norovirus is very infectious and transmits: 

  • following close contact with an infected person when they are symptomatic with diarrhoea and/or vomiting
  • by eating undercooked shellfish that may have been sourced from polluted waters
  • from food contaminated with the virus
  • by touching contaminated surfaces and not washing hands with liquid soap and water

General guidance

Contact precautions – Contact precautions are required for patients known or suspected to have Norovirus. Click here for link to contact precautions.

Hand Hygiene - Wash hands with soap and water after contact with affected patients or their environment and after removal of personal protective equipment

PPE - Use disposable gloves & aprons for all contact with patients, their environment, and when dealing with blood or bodily fluids

Isolation - All cases of Norovirus should be isolated in a single room or cohorted into one area

Cleaning - Equipment required

  • Disposable gloves and aprons
  • Disposable household waste bags
  • Detergent and hypochlorite solution or a combined detergent and hypochlorite solution (1000 ppm of available chlorine). Alternatively a chlorine dioxide solution can be used
  • Disposable paper towel/roll and disposable cloths
  • Plastic bucket and warm water

Cleaning – Process

Every healthcare facility should have written protocols to guide routine, enhanced and terminal general cleaning and to ensure that all areas of the environment are regularly cleaned to a satisfactory standard. Click here for full cleaning and disinfection guidance (insert link to cleaning and disinfection section of  the manual)

Note – for large spills of vomit and/or faeces the following action should be taken:

Employ the 4 ‘C’s’ and undertake the following actions:

  • Cordon off the area. Ensure that the area where the spillage takes place is cordoned off and there is no access to guests/visitors. Put on disposable gloves and an apron
  • Cover the spillage with disposable paper towels/roll and allow spillage to absorb the free liquid. Pour hypochlorite solution onto towels/roll and leave for 3-5minutes (do not use hypochlorite solution on carpets/soft furnishings
  • Clear the spillage. Lift the soiled paper towels/roll, removing as much of the spill as possible and place in a disposable household waste bag
  • Clean the area using a neutral detergent and water

Record keeping - Make a list of affected patients with date of onset of diarrhoea or vomiting. If admitted to hospital, note the date and reason for admission. Note whether on laxatives or on antibiotics

Seek advice - Inform the Infection Prevention Control Team (IPCT) if gastroenteritis is suspected. In non-hospital healthcare settings the first contact for advice may be the Home/unit manager, the GP and the Public Health Agency

Are other patients or staff affected? - If an outbreak is suspected, follow guidance in policy for Outbreak Management

Samples - If an outbreak of Norovirus is suspected send specimens to the Regional Virology Laboratory for testing (under the direction of the IPC team in the hospital or PHA in a Care Home setting). Diarrhoeal stools from hospital patients should also be sent for culture (O&S) and C. difficile toxin testing

Visitors - Visitors do not need to wear protective clothing unless they are providing direct care to a patient, but should be advised to wash their hands with soap and water before entering or leaving the room and not to visit other patients at the same time

Transfer of patients. Symptomatic patients should not be moved to other wards, hospitals or facilities. Medically urgent cases may be transferred after discussion with the IPCT. The receiving hospital/ residential facility must be advised

Norovirus Outbreaks – what is an outbreak?

An outbreak should be considered when there are:

  • Two or more people experiencing a similar illness and are linked in time and/or place
  • A greater than expected rate of infection compared with the usual background rate for the place and time where the outbreak has occurred
  • A suspected, anticipated or actual event involving microbial or chemical contamination of food or water

Click here for full guidance on outbreak management

A Norovirus outbreak typically presents with staff and/or patients affected and vomiting is a major feature. In this situation the IPC team (or PHA for Care Homes) should be contacted and all precautions should be implemented IMMEDIATELY (including out of hours).

Patient management in Norovirus Outbreaks

  • Remove clutter from the environment. It is particularly important to remove foodstuffs (including fruit) from the patients’ locker tops.
  • In significant outbreaks it may be necessary to close a ward/ unit to new admissions. This decision is made in consultation with the Infection Prevention Control Team in acute settings or the PHA in community settings.
  • Ensure that the domestic supervisor is informed of the situation as soon as it arises. Extra cleaning and domestic staff may be needed. Cleaning frequency in the affected area should be increased. (insert link to cleaning and disinfecting section).
  • The room (and any associated patient equipment e.g. commode) must be cleaned at least daily and disinfected using a solution of a sodium hypochlorite (1000 ppm available chlorine) or chlorine dioxide solution, then rinsed and dried.
  • Visiting should not come into hospital when they are symptomatic with vomiting and/or diarrhoea or within 48hours of having symptoms.

Staff Management in Norovirus Outbreaks

  • Norovirus frequently affects staff as well as patients.
  • A staff member with symptoms should go off work promptly and not return until symptom free for 48 hours; food handlers should not return until symptom free for 72 hours.
  • Staff should leave and return to work on the advice of the Occupational Health Department. Staff should submit specimens if requested, as this may help define the cause of the outbreak.
  • Staff movement may need to be restricted during an outbreak and staff from affected areas should not work in unaffected areas.

Click here for Norovirus information leaflet

Note: Staff should also refer to their local IPC policies and procedures for Norovirus/Outbreak management.


1. Guidelines for the management of norovirus outbreaks in acute and community health and social care settings. Available at:
2. HPS Norovirus Outbreak Guidance Season – preparedness, control measures & practical considerations for optimal patient safety and service continuation in hospitals. Available at: