Don’t Panic Addendum, 10 May 2009

2009/05/10

First, a clarification: the previous projections I posted regarding the potential death toll for an Influenza A (H1N1) pandemic assumed no variation from country to country with regards to differences in standards of health care. The projections were an abstract analysis that assumed a fixed mortality rate for the entire world population, regardless of regional mitigating factors. Given that standards of health care in the USA, Canada, western Europe, etc., are much higher than elsewhere in the world, the death toll in these locations is likely to be far lower, especially considering that the virus is, thus far, relatively non-fatal. If it does spread as quickly as the WHO pandemic predictions indicate, I suspect that even in countries that have high standards of care, the death toll would be non-trivial, but in terms of percentages, we would likely be looking at absurdly small ones.

This leads to the most current report issued by the WHO, which contains revised statistics. [1] Based on the new data, this makes the abstract analysis even less dire than previously indicated. Since there was only two additional deaths reported, but a jump of nearly 1,500 new cases, the overall mortality rate comes to 1.385% (48 deaths / 3,440 confirmed infections = 0.01395; 0.01395 x 100 = 1.395%). The difference between this figure and the previous (1.84%) is not particularly noticeable, but yields a difference of just under 9 million fewer deaths (2,000,000,000 x 0.01395 = 27,900,000; previously calculated death toll = 36,800,000; 36,800,000 – 27,900,000 = 8,900,000) in the abstract analysis; certainly a non-trivial amount.

In addition to the abstract analysis, a slightly more nuanced analysis accounting for differences in standards of health care might also be useful. Based on the current statistics, it is likely that most developed nations would suffer a mortality rate of far less than 1% (combined statistics for the USA and Canada: 3 deaths / 1,881 confirmed cases = 0.0016; 0.0016 x 100 = 0.16%); assuming that 1/3rd of the population of the USA were infected (based on the WHO estimate that 2 billion of the world’s 6 billion could be infected; 2/6 = 1/3), this would yield a total of roughly 160,000 deaths (1/3rd of the US population is 100 million; 100,000,000 x 0.0016 = 160,000). Considering that from January to mid-April, roughly 11,000 people died from regular influenza, [2] this would yield a yearly total of approximately 41,600; [3] as such, the death toll from the H1N1 strain would be roughly four times higher, so it would be noticeably different from a typical flu season.

On the other hand, the mortality rate for third world countries [4] is likely to be worse than the figures for the USA. Taking the figures for Mexico as a baseline, the mortality rate is significantly higher than that for the USA: 3.29% for the former versus 0.16% for the latter. [5] Given Mexico’s population of approximately 111,211,000, [6] a similar calculation as in the previous paragraph indicates that there could be up to 1,220,000 deaths; [7] note that this is 7.625 times greater than the death toll for the USA, even though the USA has roughly three times the total population of Mexico (current US population being roughly 300 million). Of course, health care is not the only factor affecting these discrepencies; hygiene, population density, domestic habits, etc., could also affect the outcome, though it is far outside my area of expertise to coherently comment on these factors. Again, my primary goal in pointing out these figures is to illustrate that, for our nation at least, there is little reason to panic over the Influenza A (H1N1) outbreaks; it still seems unlikely that we are facing a new Black Death in this particular virus.

Notes:

[1]: Full text of Influenza A (H1N1) update 23 available here, from the WHO website, updated 09 May 2009.

[2]: CNN article, 28 April 2009; note that this article was written prior to the confirmation of two H1N1-related deaths in the USA, hence the reference to “no confirmed deaths” in the opening statement.

[3]: Assuming the CNN article’s figures are averages, for a full year of 52 weeks with 800 deaths per week, the overall death toll would be 41,600. This, of course, is an abstract worst-case scenario, since the flu season does not last all year.

[4]: Yeah, yeah, I know…the politically sensitive term is “developing nations,” but I don’t care. Sue me.

[5]: The WHO has confirmed 45 deaths out of 1,364 confirmed cases in Mexico; 45 / 1,364 = o.0329; 0.0329 x 100 = 3.29%

[6]: Mexican statistics available here, from the CIA World Factbook website; updated 23 April 2009. Note that the population estimate is for 2008.

[7]: Total Mexican domestic population = 111,211,789; 1/3rd infection rate yields 37,070,596 total infections (111,211,789 / 3 = 37,050,596); 37,050,596 x .0329 = 1,219,622.

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