Source – WHO as of 6/7/12
# 6401
One of the more contentious aspects of the H5N1 research debate of the past 8 months has been the argument over the `real’ CFR (Case Fatality Ratio) of the H5N1 virus in humans.
The `official’ number – a fatality rate of roughly 60% – is derived from the total known human infections by the virus (606 as of June 7th, 2012), and the total number of fatalities within that group (357)
Critics point out that only the sickest of the sick would end up in a testing environment, and that many mild cases would recover and never be counted.
The numbers, they maintain, are badly skewed.
Last February (see Science: Peter Palese On The CFR of H5N1) the journal Science published a meta-analysis by Taia T. Wang, Michael K. Parides & Peter Palese, that argued that we are likely missing a great many H5N1 infections (perhaps millions), and that the virus is far less lethal than has been assumed in the past.
That argument was countered by CIDRAP director Michael T. Osterholm and Nick Kelley in an mBio article, where they found little serological evidence to suggest that we are missing `millions’ of uncounted H5N1 infections (see mBio: Mammalian-Transmissible H5N1 Influenza: Facts and Perspective).
Today, we’ve a new response to the Palese meta-analysis appearing in the journal Science. One with a remarkable pedigree; attached you’ll find some of the biggest names in influenza research:
Comment on “Seroevidence for H5N1 Influenza Infections in Humans: Meta-Analysis”
Science 22 June 2012:
Vol. 336 no. 6088 p. 1506
DOI: 10.1126/science.1221434Maria D. Van Kerkhove, Steven Riley,Marc Lipsitch, Yi Guan, Arnold S. Monto, Robert G. Webster, Maria Zambon, Angus Nicoll, J. S. Malik Peiris, Neil M. Ferguson
Abstract
A better understanding of the severity of H5N1 in humans is needed. Wang et al. (Brevia, 23 March 2012, p. 1463; published online 23 February 2012) over interpret the results of seroprevalence studies and take too little account of underlying uncertainties. Although the true risk of death from H5N1 infection will likely be lower than the 60% of reported laboratory-confirmed cases, there is little evidence of millions of missed infections.
Their entire rationale may be read here, and it strongly counters the assessment presented by Wang et al. in the original paper.
Dueling opinion pieces, regardless of the credentials of those involved, can’t really settle this argument. What we need are more, and better, seroprevalence studies in places where the H5N1 virus is endemic to come to any firm conclusions.
While most researchers accept that the 60% CFR number is probably far too high, as the authors of today’s article caution, in the absence of compelling data to the contrary:
“The precautionary principle dictates that we continue to assume that natural H5N1 infection in humans carries a high risk of death”
A policy I would certainly endorse.
