Influenza

Pandemic Influenza Special Investigations & Studies (PSS)

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In the early stages of the emergence of a novel influenza virus with efficient human-to-human transmission, generating and gathering epidemiological, virologic, and clinical data, including severity and transmissibility parameters, is critical to rapidly assess the situation and to guide response actions.

The Pandemic Influenza Special Investigations & Studies (PSS) provide a generic preparedness and readiness framework for conducting detailed investigations and studies critical for risk assessment of an outbreak caused by a novel influenza virus. These targeted investigations will supplement routine surveillance systems to address specific questions in the early stages of a pandemic.

WHO, with the support of a Technical Expert Working Group, is developing generic protocols and is building a network of sites which could conduct these investigations and studies at the time of a pandemic.

Protocols

Three case and contact investigation protocols have been prioritized and been developed.

1. The 'First Few X' cases and contact' investigation protocol (FFX) (currently under finalization through piloting)

The FFX protocol will be the primary PSS to be initiated at the start of a pandemic. Presenting a rapid glimpse of the situation, it will generate evidence for a public health response, an early understanding of some of the key clinical, epidemiological and virological characteristics of the first cases of a novel influenza virus infection and their close contacts. It will also provide early estimates of most epidemiological parameters which can then be used for forecasting and other purposes.

The FFX protocol can be complemented, expanded or reinforced by other studies.

2. The 'household transmission' investigation protocol (currently under finalization)

This investigation aims to prospectively collect information on important epidemiologic parameters in a subset of laboratory-confirmed cases and their household contacts in the early stages of a pandemic.

3. The 'closed setting transmission' investigation protocol (currently under finalization)

This investigation aims to prospectively collect information on important epidemiologic parameters within closed-settings, which are defined as epidemiological units larger than a household and can include schools, hostels, camps, healthcare facilities with frequent visitors, prisons, military facilities and others.

A network of sites

For the PSS to be operational during a pandemic, WHO is building a global network of sites, which can be primed to conduct one or more PSS in the event of a pandemic. Data-sharing and other processes involving multi-site data will be coordinated by WHO.

Outcome

Data generated from the PSS are expected to:

  • provide insight into key transmissibility and severity parameters,
  • support forecasting of the course of the pandemic,
  • aid identification of population groups in need of targeted interventions,
  • inform global and country level risk assessments.

The outputs of the multi-site network and the readily-available generic protocols enhances country and global preparedness and readiness and facilitates rapid operational research at the time of the next influenza pandemic.

Contact information

Global Influenza Programme
World Health Organization
Avenue Appia 20
1211 Geneva 27
Switzerland
Email: WHOinfluenza@who.int .