Influenza

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  • See also       

    Fever in returned traveller
    Febrile Child

    Key Points

    1. Most influenza in healthy children is self-limiting and uncomplicated.
    2. Some chronic illnesses predispose children to higher risk of severe disease, but up to half of severe cases occur in previously well children.
    3. In hospitalised children with severe disease, antiviral treatment should be commenced empirically if less than 48 hours since the onset.
    4. In an unwell child, presence of influenza does not exclude co-existing serious bacterial infection.

    Background

    • Incubation period is 1-4 days (average 2 days)
    • Hand and respiratory hygiene (e.g. covering the mouth when coughing) reduce transmission
    • Infectious period is from 24 hours prior to onset of symptoms for 4-7 days of illness. This can be prolonged in young children or those with immunodeficiency

    Assessment

    Clinical features of uncomplicated influenza

    • fever (one third of children have fever without other symptoms)
    • rigors or chills
    • respiratory symptoms: rhinorrhoea, sore throat, cough, croup, otitis media
    • headache
    • myalgia, arthralgia
    • lethargy, malaise
    • less common: conjunctivitis, abdominal pain, nausea and vomiting

    Younger children may be

    • less likely to have respiratory features
    • more likely to have febrile seizures
    • more likely to have gastrointestinal features
    • more likely to have severe disease – see febrile child

    Complications of severe influenza

    • pneumonia
    • secondary bacterial infection especially S. aureusand S. pneumoniae
    • respiratory failure
    • neurological complications
      • encephalopathy / encephalitis
      • aseptic meningitis
      • Guillain-Barre Syndrome
      • cerebellar ataxia
    • myositis and rhabdomyolysis
    • myocarditis and pericarditis
    • Reye syndrome (associated with aspirin use) 

    Risk factors for severe disease – consider treatment

    • Severe chronic disease, particularly
      • Neurological
      • Respiratory
      • Cardiac
      • Haematological e.g. Sickle Cell Disease
    • Genetic condition e.g. Trisomy 21
    • Premature infant
    • Immunosuppression

    Management

    Immunisation status does not affect the management of children with suspected influenza

    Investigations

    • Consider testing where confirmation is likely to influence treatment decisions - see flowchart.
    • Detection of influenza virus by nucleic acid (PCR) testing from appropriate respiratory specimen (nasal or throat swab or nasopharyngeal aspirate)

    Treatment

    Supportive care e.g. hydration and / or respiratory support

    Admitted children should be isolated (or cohorted) - discuss with hospital infection control

    influenza  

    Clinical features at presentation - indications for treatment

    Severe respiratory (e.g. pneumonia), neurological (e.g. encephalitis), cardiac (e.g. myocarditis, pericarditis), muscle (e.g rhadomyolysis) or multi-organ failure

    Antiviral treatment

    • Oseltamivir, zanamivir and peramivir are neuraminidase inhibitors that reduce influenza virus replication
      • Oseltamivir is usually first line therapy (oral or nasogastric)
    • Treatment may have a modest effect in terms of reducing duration of symptoms (1 day on average) and may prevent more severe disease
    • Treatment is most effective if started within 48 hours of onset of illness
    • Neuraminidase inhibitors have no role in treating other viral infections

    Oseltamivir

    • Oral capsule 30mg, 45mg, 75mg or oral suspension 6 mg/mL
    • Capsule contents may be dissolved in water (for use immediately)
    • Side effects
      • headache
      • nausea and vomiting (reduce by giving with food), twice as likely to have vomiting (from 4% to 8% of unwell children)
    • For use in renal impairment – seek advice

    Oseltamivir dosage

    Weight Doses (oral) Duration
    Treatment
    Birth (term) - 12 months 3mg/kg/dose BD 5 days
    1-18 years
    <15 kg 30mg BD
    15-23kg 45 mg BD
    23-40kg 60mg BD
    <40kg 75mg BD
    Prophylaxis
    Birth (term) -12 months 3mg/kg/dose daily 10 days
    1-18 years
    <15 kg 30mg daily
    15-23kg 45 mg daily
    23-40kg 60mg daily
    <40kg 75mg daily

    *doses based on AMH

    Peramivir

    • Seek specialist advice - for inpatient use only
    • Only children over 2 years
    • IV preparation - used when enteral route not appropriate

    Consider consultation with local paediatric team when

    Child with suspected influenza and risk factors 

    Consider transfer when

    Children requiring care above the level of comfort of the local hospital
    Child with severe disease

    For emergency advice and paediatric or neonatal ICU transfers, see Retrieval Services. 

    Consider discharge when

    Well child and educated to monitor for complications 

    Parent information

    RCH Kids Health Info Fact Sheet 
    NSW Children’s Hospital Fact Sheets  

    Additional notes

    Influenza vaccine

    • The best available preventative measure against influenza
    • Recommended for all people aged >6 months annually
      • Strongly recommended and funded for children ≥ 6 months and <5 years
      • Strongly recommended and funded for all children of ATSI background, children with risk factors for severe influenza and pregnant women
    • More information is available from the Australian Immunisation Handbook and the ATAGI annual position statement.

    Prophylaxis of contacts

    In hospital contact

    • significant exposure is classified as being within 1 metre > 15 mins without personal protective equipment

    After significant exposure, suggest oseltamivir (prophylaxis) for children and family members if

    • they have risk factors
    • have household contacts with risk factors
    • household contacts who:
      • age ≥ 65 years 
      • women who are pregnant or within 2 weeks after delivery

    Last updated September, 2019

  • Reference List

    1. Blyth, C et al. Influenza Epidemiology, Vaccine Coverage and Vaccine Effectiveness in Children Admitted to Sentinel Australian Hospitals in 2017: Results from the PAEDS-FluCAN Collaboration. Clin Infect Dis. 2019. 68(6):940-948.
    2. Chaves, S et al.The Burden of Influenza Hospitalizations in Infants From 2003 to 2012, United States. The Pediatric Infectious Disease Journal. 2014. 33(9).  
    3. Clinical Practice Guidelines by the Infectious Diseases Society of America: 2018 Update on Diagnosis, Treatment, Chemoprophylaxis, and Institutional Outbreak Management of Seasonal Influenza, IDSA. Retrieved from https://www.idsociety.org/globalassets/idsa/practice-guidelines/2018-seasonal-influenza.pdf (viewed July 2019).
    4. Committee on Infectious Diseases, American Academy of Pediatrics. Recommendations for Prevention and Control of Influenza in Children, 2018-2019. PEDIATRICS. 2018. 142(4).
    5. Gill, P et al. Identification of children at risk of influenza-related complications in primary and ambulatory care: a systematic review and meta-analysis. Lancet Respir Med. 2015; 3: 139–49.
    6. Jefferson T et al. Neuraminidase inhibitors for preventing and treating influenza in adults and children. Cochrane Database of Systematic Reviews. 2014.
    7. Jefferson, T et al. Oseltamivir for influenza in adults and children: systematic review of clinical study reports and summary of regulatory comments. BMJ 2014. 348.
    8. McVernon J. Controversies in medicine: the rise and fall of the challenge to Tamiflu, The Conversation. Retrieved from https://theconversation.com/controversies-in-medicine-the-rise-and-fall-of-the-challenge-to-tamiflu-38287 (viewed 28 July 2019).
    9. Muthuri, S et al. Impact of neuraminidase inhibitor treatment on outcomes of public health importance during the 2009-2010 influenza A(H1N1) pandemic: a systematic review and meta-analysis in hospitalized patients. J Infect Dis.2013.207(4):553-63.
    10. NICE Guideline: Amantadine, oseltamivir and zanamivir for the treatment of influenza. Retrieved from https://www.nice.org.uk/guidance/ta168/chapter/1-Guidance (viewed 15 July 2019).
    11. Poehling, K et al. The Burden of Influenza in Young Children, 2004–2009. PEDIATRICS. 2013. 131(2).  
    12. Red Book. 2015. American Academy of Pediatrics. Retrieved from https://redbook.solutions.aap.org/chapter.aspx?sectionid=189640115&bookid=2205 (viewed July 2019).
    13. Sasich L. WHO downgrades oseltamivir on drugs list after reviewing evidence. BMJ. 2017. 357.
    14. Seasonal influenza in children: Clinical features and diagnosis, UpToDate Retrieved from  https://www.uptodate.com/contents/seasonal-influenza-in-children-clinical-features-and-diagnosis?search=influenza&source=search_result&selectedTitle=1~150&usage_type=default&display_rank=1 (viewed 6 June 2019).
    15. Silvennoinen, H et al. Clinical Presentation of Influenza in Unselected Children Treated as Outpatients. The Pediatric Infectious Disease Journal. 2009. 28(5).
    16. Upton D. The use of antiviral drugs for influenza: Guidance for practitioners. Retrieved from https://www.cps.ca/en/documents/position/antiviral-drugs-for-influenza (viewed 15 July 2019).
    17. Wilson, E et al. Starship Guideline: Influenza. Retrieved from   https://www.starship.org.nz/guidelines/influenza/ (viewed 15 July 2019).