Respiratory Viruses - Guideline for the prevention of transmission

• Summary
• Background
• Diagnosis
• Investigation
• Management
• Appendix A
• Appendix B

Summary of Guideline

Suspected or confirmed viral respiratory tract infected patients must be managed according to LTHT Isolation Guideline.

Aims
To prevent and or control the transmission of viral respiratory tract infections to patients, visitors and staff within LTHT.

Objectives
For LTHT healthcare workers (HCWs) to be aware of what measures must be implemented when managing patients with suspected ( ‘clinically diagnosed’) or confirmed (established via virological testing) viral respiratory tract infection.

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Background

Viral respiratory tract infections are common in both adults and children and can spread easily from person to person .Common causes of Viral Respiratory Infections include, Rhinovirus (Common Cold), Respiratory Syncytial Virus (RSV) and Influenza. In addition bacteria and other atypical micro-organisms may cause respiratory tract infections, some of which follow an initial viral infection.
Influenza occurs annually during the winter months and spreads within a community (seasonal ‘flu). Pandemic influenza occurs when a new influenza A subtype emerges. Unlike seasonal influenza, pandemic influenza can occur at any time of the year with symptoms which may be more severe.
Some patients are at increased risk of developing severe disease and complications of Respiratory Viruses these include patients with:

• Chronic lung, heart, kidney or neurological disease.
• Immunosuppression,
• Diabetes mellitus
• Pregnant women
• Children under 5
• People aged over 65 years
• People who are obese

Routes of Transmission
Viral respiratory tract infections can be acquired by droplet, direct, indirect and airborne routes.

Droplet transmission -
Droplets greater than 5 microns in size may be generated from the respiratory tract during coughing, sneezing or whilst talking .Droplets from an infected person can cause infection in others if they come into contact with mucous membranes such as the nose or mouth.

Airborne Transmission
Airborne transmission is the transmission of airborne particles of microns smaller than 5 microns in size. Particles less than 5 microns can stay present in the air for long periods and disperse over large distances.

Direct, Indirect Contact transmission.
Infectious organisms can be transmitted, for example, from an infectious individual who through coughing sneezing etc. into their hands can then transfer to another individual who, in the absence of correct hand hygiene, can transfer the organism to the mucous membranes e.g. mouth, nose or eyes.
Indirect contact occurs when an individual has contact with a contaminated object such as equipment, furniture that an infected individual may have coughed or sneezed on. In the absence of correct hand hygiene this may transfer the organism to the mucous membranes.

Incubation period
The incubation period is the time between exposure to an organism and the appearance of symptoms. Common incubation periods are-
Respiratory Syncytial Virus (RSV) -3-7 days
Rhinovirus - 2-4 days
Influenza - 1-4 days

Infectious period
The infectious period is the time period which an infected individual can transmit the infection to another. This varies by organism and by individual and is often assumed to be for the duration of symptoms.

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Diagnosis

Symptoms include cough, fever, headache, nasal discharge, nasal congestion, sneezing, sore throat, malaise and fatigue. Incubation times before the appearance of symptoms vary among pathogens as per Information above and these would need to be considered at the time of assessment.

Emerging and re-emerging respiratory virus infections -

If clinical signs, travel history and/or exposure suggest infection with a new or re- emerging respiratory virus such as certain Coronaviruses EG SARS and MERS the Infection Prevention and Control Team must be contacted immediately.  

• Relevant clinical features include - Fever > 38c; or history of fever and respiratory symptoms or other life-threatening illness with both geographical and exposure criteria fulfilled
• Geographical - travel in the last 2 weeks to any area of the world known to have cases of severe unexplained respiratory illness
• Exposure – within 7 days of onset of symptoms
• The patient must be source isolated immediately on admission.
• Until medical assessment provides a differential diagnosis the patient must wear a surgical mask.
• HCWs must wear a FFP3 [respirator] mask, fluid repellent long-sleeved gown and gloves

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Investigation

Swabs and transport media are available from the molecular laboratory, ext 28750 or by faxed form available on the LTHT Pathology and Laboratory Medicine (virology) web site. Nasopharyngeal aspirate is probably the best sample for young children but nose and/or throat swabs are an acceptable alternative. Samples should reach the laboratory before 10.00 weekdays and 9:00 on Saturdays (see LTHT Pathology and Laboratory Medicine - Tests & Tubes).

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Management

Isolation of Patients

• All patients with suspected or confirmed viral respiratory tract infection must be managed in source isolation as per LTHT Isolation Guideline.
• If a single room is not available then cases of the same (confirmed) viral respiratory tract infection can be nursed together as a cohort in a bay.
• Children/infants with suspected bronchiolitis during the annual RSV season (November - March) may be cohorted prior to laboratory confirmation.
• Children at high risk (see list above) must be source isolated and not cohorted.
• Outpatient areas must place patients with suspected viral respiratory tract infection in a segregated area away from other patients.
• Relatives/visitors with suspected/confirmed viral respiratory tract infection should be discouraged from visiting other than in exceptional circumstances. This includes toddlers and children accompanying visitors.

Immunocompromised patients are those who are undergoing stem cell transplantation (SCT), haematology/oncology patients, and those undergoing corticosteroid therapies and/or have other severe immunodeficiency. In this group, respiratory virus infections can further predispose to bacterial infection placing them at high risk of pneumonia. Also, in immunocompromised patients, viruses can be present for longer periods. Risks can be minimised by source isolation in

• negative pressure single rooms - these have a ventilation system designed so that air flows from the corridors, or any adjacent area, into the negative pressure room, ensuring that contaminated air cannot escape from the negative pressure room to other parts of the clinical area
• standard single rooms or positive pressure ventilated lobby (PPVL) single rooms with the doors closed.
• Immunocompromised patients who require nebulised antiviral therapy must be managed in a negative pressure or PPVL room with the door(s) closed.

If these conditions cannot be achieved the escalation procedure described in the LTHT Isolation Guideline should be followed.
Use of personal protective equipment

• In addition to single use aprons and gloves healthcare workers caring for patients with a confirmed or suspected Respiratory Virus are advised to wear a surgical face mask when in close contact with the patient. (within 3 - 6 feet/1 - 2 metres) (The introduction of this in paediatrics will be incremental)
• Eye protection is advised where it has been assessed that there is a risk of eye exposure.
• Where patients are being cohorted in one area it may be practical to apply a mask on entry to the areas and keep it on for the duration of all care activities. This must be replaced if it becomes moist or damaged and removed inside the room once the healthcare worker is more than one metre away from the patient.
• If an aerosol generating procedure (AGP) (See Appendix B) is required, then where possible, these procedures should be carried out in well-ventilated single rooms with the doors shut. Only those HCWs who are needed to undertake the procedure should be present and appropriate PPE must be used. Any HCW required to wear a filtering facepiece device (FFP3 respirator mask) should have undertaken FFP3 respirator mask ‘fit testing’ prior to using it. NB It is essential that all frequently-touched surfaces should be decontaminated after an AGP. It is considered safe to enter the room without an FFP3 respirator mask to perform this decontamination when 20 minutes have elapsed after the completion of the AGP.
• Relatives/visitors to patients with suspected/confirmed respiratory viruses who have non invasive ventilation (NIV) or high flow oscillatory ventilation (HFOV) in situ may be exposed to potentially infectious aerosols. The number of such visitors should be limited where possible. Visitors should be made aware of the risks and be offered personal protective equipment (PPE) as recommended for staff.
• If the patient is transferring to another department e.g. x ray then a face mask needs to worn for the duration of that visit.
• Influenza must be managed according to the Influenza Personal Protective Equipment (PPE) requirements (Appendix A).

Removing patients from source isolation -
It is not necessary to send repeat specimens to aid in the decision to remove a patient from source isolation. An exception might be for a ventilated patient, in whom the continued presence of symptoms may be unclear. Submission of repeat samples should be discussed with the Clinical Virologist or Clinical Microbiologist. More invasive samples such as an endotracheal aspirate or bronchoalveolar lavage will provide the most accurate result.

• Adults - source isolation must continue for 48 hrs after respiratory symptoms have resolved. If it is unclear whether or not symptoms have resolved, isolation should continue for 7 days after onset of clinical illness
• Children - source isolation must continue for 7 days after onset of clinical illness or until there are no longer any signs of respiratory infection, whichever is longer
• Immunocompromised patients - source isolation must continue for 7 days after the onset of clinical illness or until there are no longer signs of respiratory infection, whichever is longer.
• Confirmed influenza patients - source isolation must continue for 7 days from the onset of symptoms, or 5 days if treated with antivirals. . NB: different periods of isolation should be applied if specified in temporary guidance, e.g. during an Influenza pandemic or relating to antiviral resistance.

Respiratory hygiene and cough etiquette
Patients should be encouraged to use disposable single use tissues to cover the mouth and nose whilst coughing, sneezing etc. These should be disposed of straight away. Patients should be encouraged to wash their hands frequently with soap and water (especially after coughing sneezing and using tissues).

Healthcare Workers

• HCWs with suspected/confirmed viral respiratory tract infection must not look after immunocompromised patients.
• Influenza vaccine is available free of charge and is recommended for all LTHT employees via the Occupational Department.
• Any HCW, who is experiencing persistent, unexplained respiratory symptoms especially following foreign travel, must report to their General Practitioner and must not attend work.

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Personal protective equipment for care of patients with influenza

Putting on PPE
All staff should put on PPE before entering an isolation room or segregated area as follows:

Gown (or apron (illustrated) if it is not an aerosol generating procedure) Fully cover from the neck to knees and the arms to the end of the wrists, and wrap around the back. Fasten at back of neck and waist.
Surgical mask (or FFP3 respirator if it is an aerosol generating procedure) Secure ties or elastic bands at middle of head and neck (1 above, 1 below ears) Fit flexible band around bridge of nose. Fit snugly around face and below chin. Check fit of FP3 respirator.
Face visor or goggles (in aerosol generating procedures and other situations if deemed appropriate after risk assessment) Place over face and eyes and adjust to fit.
Disposable gloves - Extend to cover wrist of gown if wearing a gown.

Removing PPE

• PPE must be removed when leaving the room or segregated area in an order to minimise the risk of cross infection.
• If a single room has been used for an aerosol generating procedure, those involved in the procedure should, before leaving the room, remove gloves first, then gown, then goggles (in that order), each placed directly into clinical waste bag inside the room.
• After leaving the room remove the FFP3 respirator and dispose of it as clinical waste.
• Hand hygiene must be performed after all PPE has been removed.
• The order for removing PPE is important to reduce cross infection. The order below always applies, even if not all items of PPE have been used.

Gloves - Assume that the outside of the glove is contaminated. Hold the outside of one glove with the opposite gloved hand; peel off. Hold the removed glove in gloved hand. Slide the fingers of the ungloved hand under the remaining glove at the wrist. Peel off the second glove over the first glove. Discard into clinical waste.
Gown or apron - Assume that the front and sleeves of the gown/apron are contaminated. Break or unfasten ties. Pull gown or apron away from the neck and shoulders touching only the inside. Turn the gown inside out. Fold/roll into a bundle and discard into clinical waste.
Visor or goggles - Assume that the outside of the visor or goggles is contaminated. To remove handle by the head band or ear pieces. Discard into clinical waste.
Surgical mask or FFP3 respirator - Assume that the front of the surgical mask or FFP3 respirator is contaminated. Untie or break the bottom ties, followed by the top ties or elastic and remove the mask by handling the ties only. Discard into clinical waste.

Perform hand hygiene immediately after removing all PPE.

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Appendix B

Aerosol Generating Procedures (AGPs) - are procedures that stimulate coughing and promote generation of aerosols. From the available literature and incorporating UK expert opinion, the following procedures are considered likely to generate aerosols capable of transmitting respiratory pathogens when undertaken on patients with a viral respiratory tract infection -  

• Intubation, extubation and related procedures, for example manual ventilation and open suctioning
• Cardiopulmonary resuscitation
• Bronchoscopy
• Surgery and post mortem procedures in which high-speed devices are used
• Non Invasive Ventilation (NIV) e.g. Bilevel Positive Airway Pressure Ventilation (BiPAP) and Continuous Positive Airway Pressure Ventilation (CPAP)
• High Frequency Oscillatory Ventilation (HFOV)
• Induction of sputum

NB - Certain other procedures/equipment may generate an aerosol from material other than patients’ secretions but are NOT considered to represent a significant infectious risk. Procedures in this category are -

• Administration of pressurised humidified 0₂
  • Administration of medication via nebulisation - During nebulisation, the aerosol derives from a non-patient source (the fluid in the nebuliser chamber) and does
  • not carry patient-derived viral particles. If a particle in the aerosol coalesces with a contaminated mucous membrane, it will cease to be airborne and therefore will not be part of an aerosol.