Sunday, May 28, 2006

Pandemic alert: phase shift?

I don't want to get in the business of defending WHO, especially as I have much to criticize about how they have done some things. But it is important to explain and clarify what they are doing or trying to do. If that sounds like a defense, you'll have to deal with it.

Helen Branswell of Canadian Press has just put out an important story saying that WHO isn't going to change the pandemic alert from Phase 3 to Phase 4, despite the fact that Phase 4 now sounds like the most appropriate description. Instead, they are going to rewrite the description to better express what they think about the threat. Some will immediately interpret this as moving the goal line when the game is going badly. Still, the explanation merits serious consideration. The phasing rewrite is in progress so I can't report what it will look like, but from Branswell's story I can at least tell you the rationale.
The worrisome Indonesian cluster -- the largest to date and the first time person-to-person-to-person spread of the virus is believed to have taken place -- has provoked calls from some quarters to change the global pandemic alert level to Phase 4 from the current Phase 3.

Before it could consider making that change, the WHO would have to convene a panel of experts -- the task force Fukuda mentioned -- to comb through the accumulated scientific data looking for evidence H5N1 viruses are becoming more transmissible to and among people and therefore pose a greater pandemic risk.

The task force would advise the WHO. But the final decision rests with the Geneva-based global health agency.

The current pandemic phasing document is a six-step ladder going from no known pandemic threat (Phase 1) to a full-blown pandemic (Phase 6). Many experts admit it's hard to see the difference between Phase 3 (no human-to-human spread or rare instances where a person has had close contact with an infected person), Phase 4 (small clusters of limited and localized person-to-person spread) and Phase 5 (larger but still localized clusters of human-to-human spread). (Helen Branswell, Canadian Press)
With experience the defects in the original formulation of the guidelines are becoming apparent. The issue, as Fukuda points out, is whether there is new evidence of altered transmissibility of the virus, not how many clusters or even their size. Much hinges on the ability to detect this kind of change, which is certainly not an easy call given our current knowledge. On the other hand, it is not especially useful to be tied to a grading system that doesn't express the risk, especially as a change in the Phasing will have immediate consequences regarding public perception, staffing, international trade, travel and commerce and much else. It's not something you want to get wrong in either direction. WHO is between the proverbial rock and a hard place.

The significance of all this may not be apparent to those unfamiliar with WHO's role in the international system and the legal and political limitations it implies. I am hoping to write some kind of explanation of this confusing issue in the near future, but for now, let's just observe that like any entity bound by rules of conduct, WHO cannot blithely toss them aside when it suits them unless the urgency is so great there is no choice. Making that call is difficult and they only get one chance. If they guess wrong, the next time they may find they have used up all their capital.

My appreciation for the difficult position WHO finds itself in won't stop me from offering advice. They need all the advice they can get.

Let me start here: release the sequences under your control.