Guidelines for the Prevention and Control of Influenza Outbreaks in Residential Care Facilities for Public Health Units in Australia

4.3 The Investigation

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The OIMT can use the following steps and the Summary Flowchart (see page 4) as a guide to investigating the outbreak. The “Respiratory Outbreak Control Measures chart” (Appendix 2) and “Checklist for Investigation and Management” (Appendix 3) may also be useful in outbreak management.

4.3.1 Formulate an outbreak name and working case definition

Formulate an outbreak name and ensure that the working case definition is appropriate and fits the criteria as defined in Chapter 3.

4.3.2 Define the population at risk

The population at risk in the facility should include the total number of residents (on site at the time of the outbreak and during the identified incubation period) and staff (including casual workers, volunteers and non-resident care staff) working at the facility. The population at risk could also be defined by obvious cohorting; for example, if the outbreak is restricted to a unit, the number of residents in that unit and staff at risk should be identified.

4.3.3 Active case finding

Line listing provides for rapid assessment of the extent and nature of the outbreak. The facility should use the “Resident line-listing worksheet” (Appendix 4) to collect data about residents with symptoms, and those who have been ill but have recovered, within the suspected time frame of the outbreak. As the investigation proceeds, data collection may be expanded to include other relevant data beyond what is recommended here. For large facilities, keeping a separate line listing for each unit affected by the outbreak may be useful. A separate “Staff line listing worksheet” (Appendix 5) should be completed for staff who have symptoms, and note made of any other facilities that staff may also work at.

Influenza and pneumococcal vaccination coverage for residents and the influenza vaccination coverage in staff collected for the line listings can be summarised and returned to the PHU (see Appendix 6 for the appropriate form).

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4.3.4. Other items to be considered by the OIMT

Confirm how and when communications will take place between the facility and the PHU.

Inform the state/territory Communicable Disease Control Unit.

Review control measures necessary to prevent the outbreak from spreading, and discuss with the facility management the responsibility for ensuring that agreed control measures are in place and enforced.

Consider the need for further specimen collection. Determine the type and number of further specimens to be taken and which residents and staff should be tested.

Notify the laboratory about the investigation. Clarify who is to receive results (both positive and negative) and by what method. Review the process for communicating laboratory results to the PHU and the facility’s designated officer.

Identify persons/institutions requiring notification of the outbreak:

• families of residents in the facility
• health care providers, e.g., general practitioner s (GPs), physiotherapists
• infectious disease physicians
• infection control practitioners
• hospital emergency departments and medical superintendents
• Coroner’s office
• other RCFs.

Discuss the necessity for vaccination of unimmunised residents and staff, and how this is to be organized.

Discuss use of antiviral medications for treatment of cases and/or prophylaxis of well residents and unimmunised staff.

Discuss whether a media release is appropriate.

Consider preparing a ministerial briefing.

Decide how frequently the OIMT will meet and set next meeting.

4.3.5 Site visit and support to the facility

Whether or not a site visit is required can be decided locally, according to the situation and capacity of the PHU. A site visit may assist in expediting specimen collection.

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