×
We're aware of a cyber security incident affecting the electronic prescriptions provider MediSecure. The eRX Script Exchange (eRX) and the National Prescription Delivery Service (NPDS) continue to operate as usual and have not been impacted. Find out more and read our statement here.

Managing pandemic influenza in general practice

Part A - Introduction

About pandemic influenza

Last revised: 16 Dec 2019

Influenza is an illness of the respiratory tract caused by one of a number of influenza viruses. There are three virus types: influenza A, B and C. Influenza C causes only mild and usually sporadic respiratory illness. Regional and widespread epidemics are most often attributed to influenza A or B. Influenza A – which is found in humans and animals – causes the most severe disease and is the only type known to cause influenza pandemics.

Influenza A and B viruses have two main proteins on the outside of the virus: haemagglutinin (HA), which helps the virus enter the host respiratory cells, and neuraminidase (NA), which facilitates the release of virus particles from infected host cells. These proteins (also called antigens) are used in naming various viruses; for example, H5N1 is avian influenza or ‘bird flu’. H1N1 is also known as ‘swine flu’ and was the cause of the 2009 pandemic.

Influenza viruses have a high mutation rate – where the H and N antigens undergo change. Small mutations (called antigenic drift) are common and every 1–2 years virus change is seen. These changes are the cause of seasonal flu epidemics. The changes to the virus mean that little immunity is gained from previous infection, exposure or vaccination. This is why a new seasonal influenza vaccine is required each year.

Large mutations (called antigenic shift) cause the emergence of a new virus and the potential for a pandemic as there is no immunity in the population. Without any immunity, the virus can spread quickly from person to person, worldwide.

Three distinct influenza scenarios may be encountered in general practice:

  • seasonal influenza, which occurs each winter. Most people experience 1–2 weeks of symptoms that are unpleasant but not usually life-threatening, except in the very young, pregnant women, or people with chronic health diseases
  • epidemic influenza, which occurs when a new highly pathogenic and more severe influenza strain emerges. This can result in increased mortality and morbidity in local populations, especially in at-risk groups
  • pandemic influenza, which occurs when a new highly pathogenic influenza strain emerges and spreads globally.

Seasonal influenza and pandemic influenza cause the same (or very similar) signs and symptoms. However, how often the influenza occurs, who gets ill and the severity of the disease may be quite different. Table 1 shows similarities and differences between seasonal and pandemic flu.

Seasonal influenza imposes a moderate but variable burden every year. The WHO estimates that seasonal influenza causes between 250,000 and 500,000 deaths worldwide each year.7

Unlike seasonal influenza, it is impossible to predict when and where the next pandemic will start, how quickly it will spread and what impact it will have on public health. The majority of deaths from seasonal influenza occur among people aged 65 years or older, but in a pandemic the proportion of deaths among the young increases.8
 

As was seen with the 2009 H1N1 pandemic, high death rates are not necessarily a feature of all influenza pandemics. Australia experienced 20-fold less mortality than several countries in the Americas.8

A number of factors may influence the mortality rate, including:

  • the strength (virulence) of the virus
  • the number of people infected
  • the vulnerability of the affected populations
  • implementation of public health mitigation strategies
  • the effectiveness of preventive measures
  • the number and duration of pandemic waves
  • influenza vaccination coverage in preceding seasons
  • the use of antivirals (where indicated) 
  • access to intensive care

At a national level, Australia experienced only a mild pandemic with H1N1 causing fewer deaths than seasonal influenza.9 However, not all Australians were affected equally. Aboriginal and Torres Strait Islander peoples were found to be more vulnerable than the general Australian population. Aboriginal and Torres Strait Islander peoples had a mortality rate six times higher than non-Indigenous Australians.2 Research suggests that Aboriginal and Torres Strait Islander peoples may be particularly vulnerable to future infections (eg H7N9) due to a lack of preexisting T-cell immunity.10

A pandemic is a global infectious disease outbreak. The term ‘pandemic’ relates to how the disease spreads, not how widespread it is or how many deaths occur (eg. cancer is widespread and kills many people but is not a pandemic).

From studies done by the WHO, pandemic influenza develops in three stages (also see Figure 3):

Stage 1: An influenza virus in an animal develops the ability to infect humans and cause serious disease. During this phase, the virus is not able to transmit efficiently between humans. Contact with infected animals is needed for human infection to occur.

Stage 2: Following a genetic change, the virus becomes more efficient at passing from human to human, first within small groups (eg. families or community networks) and later over wider but still localised areas.

Stage 3: Finally, the virus is able to transmit readily between humans. It spreads rapidly due to a short incubation period, period of communicability and the infectious nature of influenza. Rapid global spread is aided by extensive international travel, which takes place every day between virtually every country in the world.

Novel influenza viruses such as avian influenza (H5N1) continue to circulate globally and are a potential source for a pandemic.

Influenza symptoms develop 1–3 days after the patient becomes infected and can include:

  • fever, chills and sweating
  • sore throat
  • weakness
  • headache and generalised muscle and joint pains (legs and back)
  • a nonproductive cough that can later become severe and productive.

These symptoms can last up to approximately 1 week.

Influenza is more than a ‘bad cold’. Colds cause a runny nose, occasional mild fever but no muscle pains. Colds usually last 1–2 days. 

The influenza virus is highly infectious. This combined with a short incubation period (likely 1–3 days, maximum 7 days) and a period of viral shedding (when a person can infect others – 1 day before symptoms and up to 7 days after onset of illness in adults and up to 21 days in young children),12 accounts for the rapid spread of the influenza virus.

The primary mode of transmission is by large respiratory droplets, which can be propelled up to 1 metre from an infected person who is coughing or sneezing, onto the mouth, nose or eyes (mucous membranes) of another person.

Spread is also by direct or indirect (fomite) contact, when a person touches respiratory droplets that are on either another person or an object and then touches their own mouth or nose.

Airborne (small particles) transmission can occur in the general practice setting by particles being dispersed during the use of nebulisers, oxygen administration and intubation. These procedures should not be undertaken without appropriate personal protective equipment (PPE).

Evidence shows that physical barriers, especially hand hygiene, wearing a mask, and using social distancing or isolation of potentially infected people, are effective in preventing the spread of respiratory virus infections.13

Animal studies regarding the transmission of influenza viruses have pointed to a number of environmental factors, including relative humidity and temperature, that may influence transmission.14

Vaccines are the leading pharmacological measure for limiting the impact of pandemic influenza in the community.15

While pandemic influenza vaccines are only available some months after an outbreak starts, seasonal influenza vaccinations are developed each year. Candidate pandemic vaccines are also available for particular strains.

Seasonal influenza vaccination will not protect an individual against a pandemic influenza strain; however, it can reduce circulating influenza virus in the community and the chances that seasonal influenza will be confused with an outbreak of a novel strain.

Seasonal influenza vaccination is encouraged according to the current immunisation guidelines as outlined in the  Australian Immunisation Handbook.

Influenza vaccine is the only vaccine reformulated each year to optimise the match between vaccine and circulating virus strains. The WHO issues recommendations for the different strains of influenza viruses (type A and type B) which are included in the vaccine based on the prevailing strains in the northern and southern hemispheres. Once the recommendation is made, vaccine producers require at least 6 months to manufacture and distribute the vaccine.16 Unfortunately, not all influenza vaccines (especially influenza A) have high vaccine effectiveness.17

In the case of pandemic influenza, once the viral strain has been identified it takes at least 3–6 months for vaccination development.

The development of a vaccine that could block all strains of influenza virus is an intense area of research. There have been some promising leads but there is no vaccine for the foreseeable future.18

There were three influenza pandemics during the 20th century:

  • Spanish flu (H1N1) swept across the world in three waves in 1918 and 1919. It caused an estimated 50 million deaths worldwide (1–2% of the global population) and approximately 10,000 Australians died. The highest number of deaths was in young and healthy people aged 15–35 years; pregnant women were especially vulnerable.
  • Asian flu (H2N2) in 1957 caused approximately 2 million deaths worldwide. During the first wave, school children, young adults and pregnant women were mainly affected. In the second wave, the elderly had the highest death rates.
  • Hong Kong flu (H3N2) occurred in 1968 and 1969 and caused approximately 1 million deaths worldwide. It mainly affected the elderly.

Along with millions of deaths, these influenza pandemics caused social disruption and profound economic losses worldwide.

The first influenza pandemic this century was in 2009; it was referred to as ‘swine flu’ (H1N1). The virus contained genetic material of swine, avian and human origin.18 The virus has also been isolated in turkeys, cats and domestic ferrets.19 While the infection rate was high, there was a comparatively low mortality rate (18,449 laboratory-confirmed deaths as of 31 August 2010 by the WHO).

However, laboratory-confirmed deaths greatly underestimate the real mortality burden; for example, deaths from secondary bacterial infections and exacerbation of pre-existing chronic conditions are not recorded as being in any way related to influenza infection.8

Global mortality estimates by the Global Pandemic Mortality project suggest that there were between 123,000 and 203,000 pandemic respiratory deaths for the last 9 months of 2009 (which is approximately 10-fold higher than the WHO mortality count). The majority (62–85%) were attributed to persons under 65 years of age.8

There are more factors that are not known about a future influenza pandemic than that are known (see Table 2). The uncertainty factor makes preparedness particularly challenging.

While the 2009 pandemic was considered mild, future emerging pandemic virus strains may be highly pathogenic.18 The impact of a future pandemic will depend on its transmissibility and severity.20

  1. World Health Organization. Pandemic influenza risk management: WHO interim guidance. Geneva: WHO, 2013.
  2. Department of Health and Ageing. Review of Australia’s health sector response to pandemic (H1N1) 2009: Lessons identified. Canberra: Commonwealth of Australia, 2011.
  3. Jean-Gilles L, Hegermann-Lindencrone M, Brown C. Recommendations for good practice in pandemic preparedness: Identified through evaluation of the response to pandemic (H1N1) 2009. Copenhagen: WHO Regional Office for Europe, 2010.
  4. Moen A, Kennedy PJ, Cheng PY, MacDonald G. National inventory of core capabilities for pandemic influenza preparedness and response: Results from 36 countries with reviews in 2008 and 2010. Influenza Other Respir Viruses 2014;8:201–08.
  5. Kunin M, Engelhard D, Thomas S, Ashworth M, Piterman L. Influenza pandemic 2009/A/H1N1 management policies in primary care: A comparative analysis of three countries. Aust Health Rev 2013;37:291–99.
  6. Simonsen KA, Hunskaar S, Sandvik H, Rortveit G. Capacity and adaptations of general practice during an influenza pandemic. PLoS One 2013;8:e69408.
  7. World Health Organization. Influenza (seasonal) fact sheet. Geneva: WHO Media Centre, 2016. mediacentre/factsheets/fs211/en [Accessed 21 March 2017].
  8. Simonsen L, Spreeuwenberg P, Lustig R, et al. Global mortality estimates for the 2009 influenza pandemic from the GLaMOR project: A modeling study. PLoS Med 2013;10:e1001558.
  9. Muscatello DJ, Newall AT, Dwyer DE, Macintyre CR. Mortality attributable to seasonal and pandemic influenza, Australia, 2003 to 2009, using a novel time series smoothing approach. PLoS One 2013;8:e64734.
  10. Quiñones-Parra S, Grant E, Loh L, et al. Pre-existing CD8+ T-cell immunity to the H7N9 influenza A virus varies across ethnicities. Proc Nat Acad Sci USA 2014;111:1049–54.
  11. Collins N, Litt J, Winzenberg T, Shaw K, Moore M. Plan your pandemic – A guide for GPs. Aust Fam Physician 2008;37:794–99, 802–04.
  12. Patel MS, Phillips CB, Pearce C, Kljakovic M, Dugdale P, Glasgow N. General practice and pandemic influenza: A framework for planning and comparison of plans in five countries. PLoS One 2008;3:e2269.
  13. Larsen EL, Liverman CT (eds). Preventing transmission of pandemic influenza and other viral respiratory disease: Personal protective equipment for healthcare personnel. Update 2010. Washington: National Academies Press, 2011.
  14. Dominguez A, Castilla J, Godoy P, et al. Effectiveness of pandemic and seasonal influenza vaccines in preventing pandemic influenza-associated hospitalization. Vaccine 2012;30:5644–50.
  15. Valenciano M, Ciancio B, I-MOVE study team. I-MOVE: A European network to measure the effectiveness of influenza vaccines. Euro Surveill 2012;17(39). pii:20281.
  16. Kissling E, Valenciano M, I-MOVE Case-Control Studies Team. Early estimates of seasonal influenza vaccine effectiveness in Europe among target groups for vaccination: Results from the I-MOVE multicentre case-control study, 2011/12. Euro Surveill 2012;17(15). pii: 20146.
  17. Barberis I, Martini M, Iavarone F, Orsi A. Available influenza vaccines: Immunization strategies, history and new tools for fighting the disease. J Prev Med Hyg 2016 57(1): E41-E46.
  18. Garten RJ, Davis CT, Russell CA, et al. Antigenic and genetic characteristics of swine-origin 2009 A(H1N1) influenza viruses circulating in humans. Science 2009;325:197–201.
  19. York I, Donis RO. The 2009 pandemic influenza virus: Where did it come from, where is it now, and where is it going? Curr Top Microbiol Immunol 2013;370:241–57.
  20. Milne GJ, Halder N, Kelso JK. The cost effectiveness of pandemic influenza interventions: A pandemic severity based analysis. PLoS One 2013;8:e61504.
  21. Nelson C, Lurie N, Wasserman J, Zakowski S. Conceptualizing and defining public health emergency preparedness. Am J Public Health 2007;97(1):S9–11.
  22. Nori A, Williams MA. Pandemic preparedness – Risk management and infection control for all respiratory infection outbreaks. Aust Fam Physician 2009;38:891–95.
  23. La Torre G, Semyonov L, Mannocci A, Boccia A. Knowledge, attitude, and behaviour of public health doctors towards pandemic influenza compared to the general population in Italy. Scand J Public Health 2012;40:69–75.
  24. Godoy P, Castilla J, Delgado-Rodríguez M, et al. Effectiveness of hand hygiene and provision of information in preventing influenza cases requiring hospitalization. Prev Med 2012;54:434–39.
  25. World Health Organization. Vaccines against influenza. WHO position paper. Geneva: WHO, 2012.
  26. Department of Health. The Australian immunisation handbook. 10th edn. Canberra: NHMRC, Commonwealth of Australia, 2015.
  27. Blank PR, Bonnelye G, Ducastel A, Szucs TD. Attitudes of the general public and general practitioners in five countries towards pandemic and seasonal influenza vaccines during season 2009/2010. PLoS One 2012;7:e45450.
  28. Aguilar-Diaz Fdel C, Jimenez-Corona ME, Ponce-de-Leon-Rosales S. Influenza vaccine and healthcare workers. Arch Med Res 2011;42:652–57.
  29. Carlson AL, Budd AP, Perl TM. Control of influenza in healthcare settings: Early lessons from the 2009 pandemic. Curr Opin Infect Dis 2010;23:293–99.
  30. Bellia C, Setbon M, Zylberman P, Flahault A. Healthcare worker compliance with seasonal and pandemic influenza vaccination. Influenza Other Respir Viruses 2013;7 Suppl 2:97–104.
  31. van der Sande MA, Jacobi A, Meijer A, Wallinga J, van der Hoek W, van der Lubben M. The 2009 influenza A (H1N1) pandemic. Management and vaccination strategies in The Netherlands. Bundesgesundheitsblatt Gesundheitsforschung Gesundheitsschutz 2013;56:67–75.
  32. Devnani M. Factors associated with the willingness of health care personnel to work during an influenza public health emergency: An integrative review. Prehosp Disaster Med 2012;27:551–66.
  33. Seale H, Ward KF, Zwar N, Van D, Leask J, Macintyre CR. Examining the knowledge of and attitudes to pandemic influenza among general practice staff. Med J Aust 2010;192:378–80.
  34. Martin SD, Brown LM, Reid WM. Predictors of nurses’ intentions to work during the 2009 influenza A (H1N1) pandemic. Am J Nurs 2013;113:24–31.
  35. Council of Australian Governments. National action plan for human influenza pandemic. Canberra: Department of the Prime Minister and Cabinet, 2009. [Accessed 19 April 2017].
  36. Bocquet J, Winzenberg T, Shaw KA. Epicentre of influenza – The primary care experience in Melbourne, Victoria. Aust Fam Physician 2010;39:313–16.
  37. Fleming DM, Durnall H. Ten lessons for the next influenza pandemic – An English perspective: A personal reflection based on community surveillance data. Hum Vaccin Immunother 2012;8:138–45.
  38. Sherlaw W, Raude J. Why the French did not choose to panic: A dynamic analysis of the public response to the influenza pandemic. Sociol Health Illn 2013;35:332–44.
  39. State Emergency Management Committee Western Australia. Emergency preparedness report 2012. Government of Western Australia. West Leederville: SEMC, 2012.
  40. Angione SL, Inde Z, Beck CM, Artenstein AW, Opal SM, Tripathi A. Microdroplet sandwich real-time rt-PCR for detection of pandemic and seasonal influenza subtypes. PLoS One 2013;8:e73497.
  41. Jimenez-Garcia R, Hernández-Barrera V, Rodríguez-Rieiro C, et al. Hospitalizations from pandemic influenza infections among type 1 and 2 diabetes patients in Spain. Influenza Other Respir Viruses 2013;7:439–47. [A(H1N1) pdm09]
  42. Paich HA, Sheridan PA, Handy J, et al. Overweight and obese adult humans have a defective cellular immune response to pandemic H1N1 Influenza A virus. Obesity (Silver Spring) 2013;21:2377–86.
  43. Weeramanthri TS, Robertson AG, Dowse GK, et al. Response to pandemic (H1N1) 2009 influenza in Australia – Lessons from a state health department perspective. Aust Health Rev 2010;34:477–86.
  44. World Health Organization. Avian influenza, including influenza A (H5N1), in humans: WHO interim infection control guideline for health care facilities. Geneva: WHO, 2006.
  45. Lee A, Chuh AA. Facing the threat of influenza pandemic – Roles of and implications to general practitioners. BMC Public Health 2010;10:661.
  46. Anikeeva O, Braunack-Mayer AJ, Street JM. How will Australian general practitioners respond to an influenza pandemic? A qualitative study of ethical values. Med J Aust 2008;189:148–50.
  47. Apolloni A, Poletto C, Colizza V. Age-specific contacts and travel patterns in the spatial spread of 2009 H1N1 influenza pandemic. BMC Infect Dis 2013;13:176.
  48. National Health and Medical Research Council. Australian guidelines for the prevention and control of infection in healthcare. Canberra: NHMRC, 2010. healthcare_140616.pdf [Accessed 1 May 2017].
  49. Hall GG, Perry AG, vanDijk A, Moore KM. Influenza assessment centres: A case study of pandemic preparedness to alleviate excess emergency department volume. CJEM 2013;15:1–8.
  50. Pearce C, Shearer M, Phillips C, et al. Views of GPs and practice nurses on support needed to respond to pandemic influenza: A qualitative study. Aust Health Rev 2011;35:111–15.
  51. Etingen B, LaVela SL, Miskevics S, Goldstein B. Health information during the H1N1 influenza pandemic: Did the amount received influence infection prevention behaviors? J Community Health 2013;38:443–50.
  52. Tooher R, Collins JE, Street JM, Braunack-Mayer A, Marshall H. Community knowledge, behaviours and attitudes about the 2009 H1N1 Influenza pandemic: A systematic review. Influenza Other Respir Viruses 2013;7:1316–27.
  53. Earnshaw VA, Quinn DM. Influenza stigma during the 2009 H1N1 pandemic. J Appl Soc Psychol 2013;43:e109–14.
This event attracts CPD points and can be self recorded

Did you know you can now log your CPD with a click of a button?

Create Quick log

Advertising