# 3170
The abstract for the H1N1 Pandemic Study announced earlier today (Ferguson et. al) may be viewed at the link below.
Pandemic Potential of a Strain of Influenza A (H1N1) : Early Findings
Although it is very early in this outbreak, and influenza viruses constantly mutate, we have some preliminary numbers that would suggest the A/H1N1 virus is a bit more formidable than seasonal flu.
This virus, as it stands now, appears to have roughly the same pandemic potential as the 1957 H2N2 virus. That pandemic probably killed between 2 and 4 million people.
A pandemic comparable to the one we saw then would kill more people today, simply because there are almost 2 1/2 times as many people alive than there were 50 years ago.
From the Abstract:
Our estimates suggest that 23,000 (range 6,000-32,000) individuals had been infected in Mexico by late April, giving an estimated case fatality ratio (CFR) of 0.4% (range 0.3% to 1.5%) based on confirmed and suspect deaths reported to that time.
<snip>
Clinical attack rates in children in La Gloria were twice that in adults (<15 years-of-age: 61%,
15: 29%).
Three different epidemiological analyses gave R0 estimates in the range 1.4-1.6, while a genetic analysis gave a central estimate of 1.2.
<snip>
Transmissibility is therefore substantially higher than seasonal flu, and comparable with lower estimates of R0 obtained from previous influenza pandemics.
Also today, the World Health Organization released a report entitled:
Assessing the severity of an influenza pandemic
While the entire report is of interest, perhaps the biggest point made is about the estimated CAR (Case Attack Rate) of this new H1N1 virus:
H1N1 appears to be more contagious than seasonal influenza. The secondary attack rate of seasonal influenza ranges from 5% to 15%. Current estimates of the secondary attack rate of H1N1 range from 22% to 33%.
Obviously, scientists will be looking for more numbers over the coming weeks and months to help refine these estimates. These two reports are the beginning of the analysis . . . not the end.
No, this isn’t looking like a 1918 style pandemic. And for that we can be thankful.
But even a `mild’ pandemic has the potential to seriously disrupt (a nice word) our health care delivery system, inflict serious economic damage, and claim millions of lives.
