Pandemic (H1N1) 2009 influenza: surveillance systems

How the pandemic is being monitored

The Health Protection Agency (HPA) has internationally respected surveillance systems for monitoring and assessing the incidence and impact of influenza in England. These systems have operated effectively through the normal 'flu season' over the last few years and have informed policy, planning and evaluation of interventions (particularly the uptake of seasonal flu vaccine). These systems are central to influenza surveillance activities in a pandemic situation and are included as part of the UK's pandemic preparedness plans.

In addition to the existing influenza surveillance systems a number of systems specific to this pandemic have been implemented. These systems

• provide epidemic intelligence to inform public health action and policy decisions by assessing the severity of disease associated with this novel virus
• monitor for changes in the characteristics of the virus

In the early stages of the pandemic, during the 'containment' phase, pandemic preparedness systems provided detailed information about the evolving epidemiology, the spectrum of clinical disease, and the transmission characteristics of the disease.

In the second (current) phase of the pandemic, the 'treatment-only phase', additional surveillance includes hospital surveillance and data on assessments, authorisations and antivirals collected through the National Pandemic Flu Service (NPFS). In addition to this, mortality surveillance has expanded to include data on age-specific mortality. In both phases, the positivity rate of community-based self sampling for pandemic (H1N1) 2009 influenza has also been monitored.

Further information on surveillance systems

The surveillance systems used to monitor influenza are listed below with links provided where available. Some systems are specific to the current pandemic.  For more detailed information on the systems used please see Sources of UK Flu Data  on the seasonal influenza pages.

'Treatment-only phase' surveillance systems

These systems provide further information on the epidemiology and severity of pandemic (H1N1) 2009 influenza.

• Community-based self-sampling of pandemic (H1N1) 2009 influenza
• Hospital surveillance scheme

Pandemic Preparedness Systems (containment phase)

• Enhanced Surveillance of H1N1swl
• First Few Hundred (FF100) Cases Surveillance System   “The First Few Hundred (FF100)” Project – Epidemiological Protocol (PDF, 2.1 MB)
• Community-based self-sampling of pandemic (H1N1) 2009 influenza through NHS Direct

Seasonal influenza surveillance systems

• QFLU (as a component of Q-Surveillance)
• Virology testing component to Royal College of General Practitioners Weekly Returns Service
• HPA Regional Microbiology Network/CfI spotter practice scheme
• HPA Antiviral Resistance Monitoring and Viral Sequencing of Influenza
• Medical Officers of Schools Association (MOSA) and HPA scheme 

Generic surveillance systems

The 'generic' systems provide important information on the burden of disease, such as the impact on the NHS, numbers of severe illnesses and/or cases of secondary bacterial infection, and deaths.

• National laboratory reporting scheme
• Royal College of General Practitioners Weekly Returns Service
• NHS Direct
• Mortality monitoring
• Hospital admissions