Volume 191 - Issue 3
Summary of the Australasian Society for Infectious Diseases and the Thoracic Society of Australia and New Zealand guidelines: treatment and prevention of H1N1 influenza 09 (human swine influenza) with antiviral agents
Authors: Allen C Cheng, Dominic E Dwyer, A Thomas C Kotsimbos, Mike Starr, Tony M Korman, Jim P Buttery, Christine R Jenkins, Vicki L Krause and Paul D R Johnson
Med J Aust 2009; 191 (3): 142-145. || doi: 10.5694/j.1326-5377.2009.tb02722.x
Published online: 3 August 2009
Published online: 3 August 2009
The complete, up-to-date guidelines can be found at: http://www.mja.com.au/ public/rop/cheng/che10661_fm.html
Since the initial reports of H1N1 influenza (human swine influenza; caused by influenza A/2009/H1N1/swl) in Mexico and the United States in mid April 2009, many thousands of cases have been reported worldwide. At the time of writing, community transmission is becoming established in many areas in Australia, but the number of reported cases is likely to be an underestimate of the true incidence due to policies for testing.
These guidelines provide advice to clinicians on the use of antiviral agents for this newly emerged influenza virus. A full version of these guidelines, including all references, has been previously published online (http://www.mja.com.au/public/rop/cheng/che10661_fm.html).
Recommendations for diagnosis of influenza
In areas with established community transmission, patients presenting with an acute febrile respiratory illness (fever with cough and/or sore throat) are considered to have H1N1 influenza 09 and testing is generally not recommended.
Early in the course of the pandemic, timely influenza diagnostic tests can be used to enable targeted antiviral treatment, but will be less useful once community transmission is widespread.
Health care workers performing nose swabs or other high-risk aerosol-generating procedures (eg, suctioning, bronchoscopy or intubation) should use a particulate respirator (N95, P2 mask or equivalent), eye protection, impervious gowns, gloves, and, where possible, carry out the procedure in a negative pressure room.
The use of nasopharyngeal aspirates are not recommended because of the risk to staff.
The use of a combined nose–throat swab is recommended for diagnosis.
Specimens for viral nucleic acid detection and culture at reference laboratories should be taken for epidemiological surveillance and to monitor for drug resistance. Once the pandemic is established, this is best facilitated through existing sentinel surveillance systems.
Recommendations for treatment using antiviral agents
Antiviral treatment has been shown to reduce the duration of symptoms and may also reduce the incidence of lower respiratory tract infection.
Neuraminidase inhibitors (oseltamivir and zanamivir) are the antiviral agents of choice for H1N1 influenza 09.
The decision to treat an individual patient, particularly before the results of confirmatory testing are available, depends on three factors:
An assessment of the likelihood of influenza, based on the known prevalence of infection in the region, a history of contact and the characteristics of the illness.
An assessment of the likely benefits of treatment (Box 3), based on the presence of established complications, comorbidities and risk factors (Box 4), and the time since onset of the illness.
The phase of the pandemic and the public health policies regarding distribution of the national stockpile (Box 5).
Recommendations for treatment in adults
Antiviral treatment should only be given to patients with confirmed or suspected influenza within 48 hours of symptom onset, except in cases of severe influenza.
Treatment should be prioritised for patients with risk factors for poor outcomes, such as the morbidly obese, pregnant women, those with chronic disease (including asthma, cardiorespiratory disease, diabetes and renal failure) or immunosuppression, and those presenting with severe disease.
Recommendations for treatment in children
Antiviral treatment can be given to children as young as 1 year.
Parents should be warned of the possibility of rare neuropsychiatric symptoms related to oseltamivir use in children and adolescents.
There is a concern regarding central nervous system accumulation of neuraminidase inhibitors in infants aged under 1 year, based on animal data; a treatment decision must balance the potential benefits of treatment with potential toxicity.
Recommendations for treatment of severe influenza
Antiviral treatment should be given to hospitalised patients with severe influenza infection (especially pneumonia), even if commenced more than 48 hours after the onset of symptoms.
Antibiotic treatment should not be given routinely for influenza-like illness, but antibiotic treatment should follow established national guidelines for treatment of community-acquired pneumonia.
Recommendations for prophylaxis with antiviral agents
Updated information
We acknowledge that the evidence on which these recommendations are based is rapidly changing. In particular, estimates of disease severity and case fatality, and risk factors for severity are poorly defined at present and may influence clinical decision making. We therefore include some resources for further information.
Updates to these clinical guidelines will be posted on the websites of the Australasian Society for Infectious Diseases (ASID) (http://www.asid.net.au), the Thoracic Society of Australia and New Zealand (TSANZ) (http://www.thoracic.org.au) and the MJA (http://www.mja.com.au).
Australian resources for pandemic influenza, including links to clinical and infection control guidelines (http://www.flupandemic.gov.au) and current information on the H1N1 outbreak (http://www.healthemergency.gov.au and http://www.influenza specialistgroup.org.au).
For information on accessing personal protective equipment and antiviral medication, see links below:
http://www.emergency.health.nsw.gov.au/swineflu/professionals/index.asp (New South Wales)
http://humanswineflu.health.vic.gov.au/practitioners/index.htm (Victoria)
http://www.health.qld.gov.au/swineflu/html/hc_resources.asp (Queensland)
http://flu.sa.gov.au/Swineflu/InformationforGPs.aspx (South Australia)
http://www.public.health.wa.gov.au/3/952/3/human_swine_flu_health_providers.pm (Western Australia)
http://www.pandemic.tas.gov.au/what_does_it_mean_to_you/health_sector (Tasmania)
http://www.health.nt.gov.au/H1N1_Influenza/General_Information_Resources/index.aspx (Northern Territory)
http://health.act.gov.au/c/health?a=da&did=11044035&pid=1242181681 (Australian Capital Territory).
3 Factors to consider in deciding on likely benefits of treatment for H1N1 influenza 09 (human swine influenza) infection
Hospitalised patients
Patients with respiratory compromise
Patients with pneumonitis or secondary bacterial pneumonia
Pregnant women
Patients with chronic respiratory disease; other comorbidities (see Box 4)
Potential for transmission to others
Health care workers and first responders (eg, paramedics)
Household contact or carer of high-risk patient
4 Patients at risk of complications from influenza infection*
Pregnant women
Patients with:
chronic respiratory disease (including asthma and chronic obstructive pulmonary disease);
cardiac disease;
morbid obesity;
chronic diseases (eg, diabetes, chronic metabolic diseases, chronic renal failure, haemoglobinopathies);
chronic neurological disorders; or
impaired immunity, including HIV infection
Homeless people
- Residents of nursing homes and long-term care facilities
- Children aged 6 months – 10 years on long-term aspirin therapy
- Older people (> 65 years)
- Children < 5 years
* Adapted from the Australian immunisation handbook.1
5 Indications for antiviral treatment and prophylaxis for H1N1 influenza 09 (human swine influenza) infection, depending on likelihood of benefit and stage of pandemic
Little or no community transmission; cases identifiable via exposure history |
Limited community transmission; cases not identifiable via exposure history |
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Clinically presumed or laboratory-confirmed. Consider treatment > 48 h after onset if severe or not improving |
Clinically presumed or laboratory-confirmed. Consider treatment > 48 h after onset if severe or not improving |
Clinically presumed or laboratory-confirmed. Consider treatment > 48 h after onset if severe or not improving |
Clinically presumed or laboratory-confirmed. Consider treatment > 48 h after onset if severe or not improving |
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Health care workers, carers for patients at risk of complications within 48 h of onset of illness |
Clinically presumed (if appropriate exposure history) or laboratory-confirmed |
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Otherwise healthy adults and children > 5 y within 48 h of onset of illness |
Clinically presumed (depending on rationing policy and virulence) |
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Low likelihood of benefit (> 48 h after presentation, known high prevalence of resistance) |
Not indicated, unless severe infection present. Consider zanamivir if oseltamivir-resistant |
Not indicated, unless severe infection present. Consider zanamivir if oseltamivir-resistant |
Not indicated, unless severe infection present. Consider zanamivir if oseltamivir-resistant |
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Not generally indicated, except immunosuppressed patients and closed communities |
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Consider up to 7 days after exposure to prevent transmission |
Depends on observed incubation period and public health policy |
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* Such as pregnant women, patients with comorbidities or immunosuppression, and Indigenous Australians (Box 4). |
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Competing interests
Dominic Dwyer has undertaken clinical trials with anti-influenza drugs and new laboratory assays for Roche, GlaxoSmithKline and other companies. Jim Buttery has served as an investigator or on data-safety monitoring committees for influenza vaccine trials for Wyeth Vaccines and CSL. Paul Johnson has worked as a consultant for Biota, but not regarding antiviral drugs.
Acknowledgements
We thank the other members of the Guidelines Committee of the ASID (Bart Currie, Monica Slavin, Joe Torresi, Alison Kesson, John Ferguson, Ronan Murray) and the Swine Influenza Task Force of the TSANZ (Grant Waterer, Graeme Maguire, Louis Irving, Mark Holmes, Richard Wood-Baker, Simon Bowler). We also acknowledge the following for their comments on an earlier draft of the guidelines: Craig Dalton, David Looke, David Andresen, Tom Gottlieb, Craig Boutlis, Ian Gust, John Mills, Deb Friedman, Mark Veitch, Joshua Wolf and James McCaw.
References
- Australian Technical Advisory Group on Immunisation. Australian immunisation handbook. 9th ed. Canberra: Australian Government, 2008. 0_JIBGFBDE