Important Seasonal Influenza Update – Influenza cases higher than predicted peak

15 August 2017

Seasonal influenza activity is continuing to rise above its predicted peak and NSW Health is reporting that it is expected to remain high for the coming weeks. Hospitals are seeing increasing presentations of influenza-like symptoms to emergency departments and admissions for pneumonia remain high. Cases are more severe and numbers are trending upward faster than anticipated. General practitioners are asked to encourage patients to try and manage their symptoms at home and not attend emergency unless they are very unwell or have co-morbidities. NSW Health also request GPs to check the vaccination status of patients, particularly the elderly and those with chronic health conditions.

Key Points for General Practitioners:

  1. Influenza activity is high with multiple strains circulating
  2. Continue to encourage vaccination for high-risk patients
  3. Consider early antiviral therapy for suspected and confirmed influenza infection in high-risk patients.

Background

  • The winter influenza season started earlier than usual this year.
  • Influenza surveillance has detected a marked increase in activity in the past few weeks. Influenza activity is likely to be at its peak activity now or in the next few weeks.
  • Several strains of influenza are circulating widely in the NSW community – the A(H3N2) strain is predominant but B strains are also common.
  • There circulating strains appear to be well matched to the 2017 influenza season vaccines, and there is no evidence of antiviral resistance.

Diagnosis and testing advice

  • While influenza vaccination is the best way to prevent influenza illness, a history of influenza vaccination does not rule out the possibility of influenza virus infection in an ill patient with clinical signs and symptoms compatible with influenza.
  • When influenza is circulating widely in the community the need for diagnostic testing is reduced.
  • Diagnostic testing for influenza only needs to be undertaken where the results are likely to change patient management.

Treatment with antivirals (i.e. neuraminidase inhibitors: oseltamivir or zanamivir)

  • Clinical judgment, on the basis of the patient’s disease severity and progression, age, underlying medical conditions, likelihood of influenza, and time since onset of symptoms, is important when making antiviral treatment decisions for high-risk patients in general practice.
  • Clinical trials and observational data show that early antiviral treatment (ideally within 48 hours of onset) can shorten the duration of fever and illness symptoms, and may reduce the risk of complications from influenza (e.g. otitis media in young children, pneumonia, and respiratory failure).
  • Antiviral treatment is recommended as early as possible for any patient with suspected or confirmed influenza who is at higher risk for influenza complications (and hospitalised patients).
  • NSW Health encourages clinicians to not delay decisions about starting antiviral treatment while waiting for laboratory confirmation of influenza.
  • Note that dose adjustment of oseltamivir is required for patients with renal impairment, such as when the glomerular filtration rate (GFR) is less than 60 mL/min or the patient is on dialysis. Refer to therapeutic guidelines.

For further information visit