WHO proposes new pandemic flu alert levels

Researcher using BSL-3 precautions
Researcher using BSL-3 precautions

CDC influenza researcher conducts an experiment using BSL-3 precautions., CDC/Greg Knobloch

The World Health Organization (WHO) today proposed a new pandemic alert system, one that's designed to focus more on disease risk than geographic spread and to streamline communications to the public.

At a media briefing in Geneva today, David Harper, CBE, special adviser to the WHO's assistant director-general for health, security, and environment, said the interim guidance reflects lessons learned during the 2009 H1N1 pandemic, according to an Agence France-Presse (AFP) report.

A few months into the 2009 H1N1 pandemic the WHO faced tough questions from countries about its pandemic alert phases. During the 2009 World Health Assembly (WHA) some countries urged the WHO to go slow on declaring a full-scale pandemic, and they argued that pandemic phases should reflect the severity of the disease as well as its geographic spread.

The pandemic plans of some member states had response actions, such as the purchase of pandemic vaccine, that were triggered by the WHO's pandemic phase declarations.

At the time, WHO officials said the pandemic alert phases in use were crafted in the shadow of threat from H5N1 avian influenza, which was causing severe disease in humans. The 2009 H1N1 virus spread quickly around the world and caused mainly mild-to-moderate illness. The WHO had said it would seek expert advice to consider possible changes to its pandemic phase definitions.

The WHO described the alert phase in its interim guide for pandemic influenza risk management, which when finalized would replace its 2009 document. The new 4-phase alert system would replace the current 6-phase one that includes an additional post pandemic level.

The group issued its first pandemic preparedness guidance in 1999 and revised it twice, in 2005 and 2009, according to a WHO background document on the interim guidance. The revision also takes into account feedback from an external panel that in 2010 and 2011 reviewed how the WHO and the International Health Regulations performed during the 2009 H1N1 pandemic.

Following global information gathering on pandemic planning issues, the WHO formed an internal steering committee to revise and update the plan. In April an independent review group reviewed the draft and provided more input.

In a note e-mailed to reporters today, the WHO said it released the guidance in its interim form as a tool for managing pandemic threats, based on requests from member states. It also said countries will have an opportunity to comment on the interim guidance.

"The recent occurrence of human infections from avian influenza A (H7N9) and other respiratory diseases highlights how this new guidance could be useful to countries and international partners in managing the risks from the current situation," the WHO said in its backgrounder.

The WHO said the new pandemic planning guidance is meant to encourage countries to develop flexible pandemic risk management plans that focus on what's happening at the national and local levels. It said the document also emphasizes the importance of repeated risk assessment during outbreaks by all levels, from the WHO to local health departments.

The revised global phases are more of an "average" of the situation in all countries and don't reflect the situation in individual countries, the WHO said. For example, it said in the "alert" phase, one country might be in full response mode, while another might still be at the earlier preparedness steps.

Severity assessment is a critical component for assessing pandemic flu risk, and the new guidance includes methods for measuring severity, the WHO said.

A four-phase alert system would replace the current six-phase scheme. The new phases are:

  • Interpandemic, the period between pandemics
  • Alert, when a new subtype has been identified and increased vigilance and risk assessment are warranted
  • Pandemic, a period of global spread of a new subtype as indicated by global risk assessment based on virologic, epidemiologic, and clinical data
  • Transition, global risk drops, prompting stepdowns in global actions and response activities

Presumably, the world would be at the "alert" level for H5N1 avian flu, H7N9, and Middle East respiratory syndrome coronavirus (MERS-CoV).

In a potential pandemic situation, the WHO will appoint an Emergency Committee to advise the director-general, and a pandemic declaration would signal the need for collective global action to manage the risk, according to the WHO.

See also:

WHO interim guidance on pandemic influenza risk management

WHO FAQ on interim guidance

Jun 10 AFP story

May 26, 2009, CIDRAP News story "WHO may redefine pandemic alert phases

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