Antiviral Recommendations for Residents and Staff during a Confirmed Influenza Outbreak

There are currently two antiviral drugs that are licensed in Canada for the treatment and prophylaxis of influenza A and B, including oseltamivir (Tamiflu) and zanamivir (Ralenza). These medications are neuraminidase inhibitors which work by blocking the exit of the influenza virus from the respiratory cells, therefore preventing further replication of the virus. For this reason, when using antivirals for the treatment of influenza, it is important that they are initiated as soon as possible within 48 hours of symptom onset.

Ottawa Public Health (OPH) recommends oseltamivir as the drug of choice for both treatment and prophylaxis of residents in long-term care homes (LTCHs) for the following reasons:

  • The use of Zanamivir has not been proven effective for prophylaxis of influenza in the LTCH setting
  • Elderly individuals may have difficulty inhaling zanamivir
  • Zanamivir is not recommended for treatment or prophylaxis of Influenza in individuals with underlying respiratory conditions such as chronic obstructive pulmonary disease or asthma due to the risk of bronchospasm
  • Reimbursement for zanamivir for residents occurs only when the predominant strain is resistant to oseltamivir

Management of staff

It is important for staff to be advised upon hire about the influenza policy of the facility and/or their collective agreement, and the options available to them in the event of an influenza outbreak if they are not immunized for any reason.

When an influenza outbreak occurs, staff must obtain prescriptions for antiviral medication from their own health care provider and are responsible for their own antiviral-related expenses, unless they have coverage through a company or private health insurance plan. They are not eligible for prescription drug coverage under any circumstances from the Ontario Drug Program (ODP). Only under very specific circumstances, immunized health care workers may be eligible for reimbursement through the High Intensity Needs Fund (HINF).

During a laboratory-confirmed influenza outbreak, when the circulating strain is not well-matched by the vaccine, antiviral prophylaxis should be offered to all staff, regardless of vaccination status, until the outbreak is declared over, based on consultation with OPH.

Immunized Staff

  • Staff immunized ≥ 2 weeks prior to outbreak declaration, whether with an inactivated or live attenuated influenza vaccine (LAIV), have no  work restrictions, provided they are feeling well
  • Staff immunized ≤ 2 weeks with inactivated influenza vaccine prior to outbreak declaration, should take antiviral prophylaxis until immunity is reached or until the outbreak is declared over, whichever is shorter
  • Staff immunized ≤ 2 weeks with LAIV (Flumist) should not receive antiviral treatment or prophylaxis for at least 2 weeks after receipt of LAIV, unless medically indicated, so that the antiviral agents do not kill the replicating virus from the administered vaccine. If antiviral agents are administered within this time frame, revaccination should take place immediately with an inactivated influenza vaccine

Unimmunized Staff

  • Unimmunized staff should be offered vaccine and take antiviral prophylaxis until immunity is reached or until the outbreak is declared over, whichever is shorter
  • Unimmunized staff who refuse to be immunized must take  antiviral prophylaxis until the outbreak is declared over; staff may work with residents as soon as they start antiviral prophylaxis
  • Staff accepting to be immunized, but refusing antiviral medication, should NOT be permitted to work in the outbreak-affected area for a two week period. Prior to being reassigned to another unit, they must be asymptomatic for 72 hours (3 days)
  • Flumist is a vaccine option in Ontario that is only publicly funded for children from 2-17 years of age. If a staff member or resident chooses to be immunized with Flumist privately, it is recommended that LAIV (Flumist) not be administered until 48 hours after antiviral treatment or prophylaxis for influenza is stopped

Management of residents

Prophylaxis

  • During a laboratory-confirmed influenza outbreak, antiviral prophylaxis should be offered to all residents in the outbreak-affected area who are NOT already ill with influenza, regardless of immunization status, until the outbreak is declared over
  • If respiratory symptoms develop in a resident while on prophylaxis, the dose should be switched to a treatment dose for five days or until symptom free whichever is shorter

Treatment

Once an outbreak has been laboratory-confirmed as influenza, additional laboratory confirmation of new cases is not required to begin treatment of residents who meet case definition. It is important that:

  • Antiviral treatment of ill residents who meet case definition is started as soon as possible, and within 48 hours of symptom onset
  • Ill residents remain in their rooms for the duration of the antiviral treatment, which should be a total of five days

Circumstances that may Affect Decisions regarding Use of Antiviral Medication

  • If the resident meets case definition and has been symptomatic for MORE than 48 hours and antiviral treatment has NOT been started, use Appendix A for making decisions about the use of antivirals
  • If the outbreak is ongoing when the five-day treatment course ends AND the resident did NOT have lab-confirmed influenza (either the resident was never tested or had a negative influenza lab result), the resident should be switched to a prophylactic dose until the outbreak is declared over. This is recommended in case of a potential outbreak caused by more than one agent (See Appendix B)

When Antiviral Medications Do Not Control the Outbreak

If new cases continue to appear 72 to 96 hours after the start of antivirals, consider the following:

  • The new cases could be caused by another organism
  • There could be compliance/adherence issues
  • Resistance to the antiviral medications may have developed in the circulating strain

In the event that the outbreak is not controlled with antiviral use:

  • Consult with the OPH Outbreak Management team to determine if the antiviral agents should be continued
Recommended dosage for prophylaxis and treatment of influenza with Tamiflu for adults

Kidney function/Creatinine Clearance

Prophylaxis is given until the outbreak is declared over

Treatment for 5 days

With no known renal disease OR With renal disease and creatinine clearance >60mL/min

 

75 mg once daily

75 mg twice daily

With known renal disease and creatinine clearance of >30-60mL/min

 

75 mg on alternate days OR 30 mg once daily

75 mg once daily OR 30 mg suspension twice daily OR 30 mg capsule twice daily

With known renal disease and creatinine clearance of 10- 30 mL/min

 

30 mg every other day

 

30 mg orally once daily

Residents with renal failure (<10 mL/min)

 

No data

Single dose of 75 mg for the duration of the illness

Dialysis residents: Low-Flux HD

30 mg orally after every alternate hemodialysis session (initial dose can be started between sessions)

 

30 mg orally after every hemodialysis session (initial dose can be started between sessions)

Dialysis residents: High -Flux HD

 

No data

75 mg after each dialysis session

Dialysis residents: CAPD dialysis

30 mg orally once weekly

Administered prior to the start of dialysis

A single dose of 30 mg orally administered prior to the start of dialysis

 

Dialysis residents: CRRT high-flux dialysis

No data

30 mg daily or 75 mg every second day

 

References:

Appendix A: Influenza Outbreak antiviral treatment recommendations if treatment is not initiated within 48 hours of symptom onset

Diagram 1: Influenza Outbreak antiviral treatment recommendations if treatment is not initiated within 48 hours of symptom onset

Influenza Outbreak antiviral treatment recommendations if treatment is not initiated within 48 hours of symptom onset

  • Resident meets outbreak case definition
  • Was antiviral treatment initiated within 48 hours of symptom onset? (NO)
  • Is the resident clinically improving?
    • NO
      Provide antiviral treatment
    • YES
      Consider antiviral therapy for individuals in high risk groups*, or individuals with moderate, severe or complicated illness

* Note: please see AMMI Influenza guidelines (as current) for a definition of high-risk groups

Appendix B: Influenza Outbreak antiviral prophylaxis recommendations for Line- listed cases after completion of treatment with antiviral medication

Diagram 2: Influenza Outbreak antiviral prophylaxis recommendations for Line- listed cases after completion of treatment with antiviral medication

Influenza Outbreak antiviral prophylaxis recommendations for Line- listed cases after completion of treatment with antiviral medication

Is the outbreak still ongoing?

  • NO
    No further action required
  • YES
    • Are antivirals still being used for prophylaxis in residents on the line-listed residents' unit?

      • YES
        • Did the line-listed resident have laboratory confirmed influenza?
          • YES
            Do not provide prophylaxis. The resident would now have immunity to the influenza virus that is causing the outbreak.
          • NO
            Start on a prophylaxis dose until the outbreak is declared over.  This is a precaution in case there is an outbreak with more than one pathogen and the line-listed resident may have previously been infected with a non-influenza pathogen. 

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