Updated: 23 August 2010 (11.00am AEDT time)

Reports from laboratories suggests that influenza activity is increasing. Of the 1,963 confirmed cases of influenza diagnosed during 2010 up to 6 August, 503 have been sub-typed as pandemic (H1N1) 2009¹. 

Since the first case of pandemic (H1N1) 2009 in Australia in May 2009, there have been a total of 38,139 confirmed cases of pandemic (H1N1) 2009 in Australia as at 30 July 2010. Of these, 37,636 cases were reported in 2009 and 503 cases were reported in 2010. A total of 193 pandemic influenza-associated deaths have been reported, with 2 deaths in 2010¹.

The Australian and New Zealand Intensive Care Society (ANZICS) has reported a total of 25 ICU admissions for influenza in 2010. In total, 16 ICU admissions have been associated with pandemic (H1N1) 2009. Of these, 14 had known co-morbidities and the median age at admission was 53 years (range 19-72)¹.

As at 20 August 2010, (except in South Africa and New Zealand) overall influenza activity and rates of respiratory diseases remained low in other countries of the temperate southern hemisphere (Australia, Chile, and Argentina). In South Africa, active circulation of seasonal influenza H3N2 and type B viruses was observed during June through mid-August 2010. In Argentina, there are unconfirmed media reports of localized influenza outbreaks in at least one part of the country².

The WHO has reported a total of 302 oseltamivir resistant pandemic (H1N1) 2009 viruses since May 2009. All except one of these isolates showed the same H275Y mutation and all remain sensitive to zanamivir. The WHO Collaborating Centre in Melbourne has reported that from 1 January 2010 to 8 August 2010, no isolates (out of 58 tested) have shown resistance to oseltamivir or zanamivir by enzyme inhibition assay (EIA) and two isolates (out of 36 tested) have shown the H275Y mutation known to confer resistance to oseltamivir¹.

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Australia is in the  PROTECT phase of the pandemic⁶. The PROTECT phase recognises that the infection with Pandemic (H1N1) 2009 is not as severe as originally envisaged when the Australian Health Management Plan for Pandemic Influenza (AHMPPI) was written in 2008. PROTECT sits alongside CONTAIN and SUSTAIN phases⁵ with a greater focus on the vulnerable or people in whom the disease may be severe, and is consistent with the message from the WHO when it lifted its Pandemic Alert to 6⁵.
Key elements of the PROTECT phase are:

• Identification and early treatment of those with moderate or severe disease especially in people with respiratory difficulty.
• A focus on early treatment of people who may be vulnerable to severe outcomes. These people include pregnant women and those with respiratory disease (asthma, COAD), heart disease, diabetes, renal disease, morbid obesity, and immunosuppression.
• Control of outbreaks in institutional settings, such as special schools.
• Widespread school closures or school exclusion for students who have travelled to areas of high prevalence are no longer appropriate and will not be continued on a national basis.
• Voluntary home isolation for those with mild disease with supportive treatment only, such as over the counter medication.
• Antivirals from the national or state medical stockpiles will be provided to those people with moderate or severe disease or whose underlying conditions, after appropriate clinical assessment, could make them vulnerable to severe infection. It is not appropriate to provide antivirals to their otherwise healthy household contacts, nor will those contacts be placed into quarantine.
• Testing would focus on to identification of Pandemic (H1N1) 2009 in people with moderate or severe illness, people more vulnerable to severe illness, those in institutional settings and Indigenous Australians.
• Increased identification and monitoring of A(H1N1) hospital admissions, ICU admissions and levels of morbidity and monitoring of clinical outcomes throughout the influenza season.
• Increased sentinel testing to identify levels of community transmission and the strain of circulating influenza viruses.
• Ongoing monitoring of the virus for the emergence of antiviral resistance, genomic drift or reassortment that could herald a change to greater virulence.
• Additional border measures such as thermal screening and Health Declaration Cards will cease.

The World Health Organization (WHO) had earlier raised the level of influenza pandemic alert from phase 5 to phase 6⁴. Despite the heightened pandemic level, the WHO was clear that there should be no border closures as there is no evidence that these measures stop the spread of the disease, and there should be no travel restrictions.

Understanding of the disease continues to evolve as new countries become affected, as community-level spread extends in already affected countries, and as information is shared globally. Many countries with widespread community transmission have moved to testing only samples of ill persons and have shifted surveillance efforts to monitoring and reporting of trends. This shift has been recommended by WHO, because as the pandemic progresses, monitoring trends in disease activity can be done better by following trends in illness cases rather than trying to test all ill persons. It remains a top priority to determine which groups of people are at highest risk of serious disease so steps to best protect them can be taken.⁷

Although the risk factors for serious pandemic disease are not known definitively, risk factors such as existing cardiovascular disease, respiratory disease, diabetes and cancer currently are considered risk factors for serious pandemic (H1N1) 2009 disease. Asthma and other forms of respiratory disease have been consistently reported as underlying conditions associated with an augmented risk of severe pandemic disease in several countries. A recent report suggests obesity may be another risk factor for severe disease. Similarly, there is accumulating evidence suggesting pregnant women are at higher risk for more severe disease. A few preliminary reports also suggest increased risk of severe disease may be elevated in some minority populations, but the potential contributions of cultural, economic and social risk factors are not clear.⁷

The World Health Organisation will no longer issue the global tables showing the numbers of confirmed cases for all countries. However, as part of continued efforts to document the global spread of the H1N1 pandemic, regular updates will be provided describing the situation in the newly affected countries. WHO will continue to request that these countries report the first confirmed cases and, as far as feasible, provide weekly aggregated case numbers and descriptive epidemiology of the early cases. For countries already experiencing community-wide transmission, the focus of surveillance activities will shift to reporting against the established indicators for the monitoring of seasonal influenza activity. Those countries are no longer required to submit regular reports of individual laboratory-confirmed cases and deaths to WHO³.

Australians who wish to receive information about A(H1N1) ‘swine influenza' should contact:

• Health information - call the Australian Government hotline on 1802 007 or visit http://www.healthemergency.gov.au
• Travel advice - visit http://www.smartraveller.gov.au

References

1.    Department of Health and Ageing Australian Influenza Surveillance Report No 31.ozflu-no31-2010.pdf

2.    World Health Organisation Pandemic (H1N1) 2009 Update 114. WHO_Update_114.pdf

3.    World Health Organization Pandemic (H1N1) 2009 briefing note 3 (revised). WHO_briefing_note_3

4.    World Health Organization.  Statement from the WHO Director General on Swine Influenza.  Available here

5.    World Health Organization.  Current WHO Phase Pandemic Alert. Available here

6.  Australian Health Minister's "Protect" Media Release. Available here 18/06/2009,10:12 34.19 Kb

7.  World Health Organization Pandemic (H1N1) 2009 briefing note 4. WHO_briefing_note_4

Other useful links:

Australia:

Commonwealth Department of Health and Ageing

Australian Health Management Plan for Pandemic Influenza

International:

World Health Organization

US Centers for Disease Control and Prevention

NZ Ministry of Health