X-Message-Number: 21564
Date: Tue,  8 Apr 2003 09:53:07 -0700
Subject: SARS doubling time
From:  (Tim Freeman)

From: Ted Kaehler <>
>As of April 4th, world cases are doubling every 10 days.

Thinking about world cases is confusing because the reporting from
China has been erratic.  The number of Chinese cases allegedly jumped
instantaneously from 806 cases in China on April 1 to 1190 cases on
April 2.

April 1 had a remarkable jump too because of the infected apartment
building in Hong Kong.  I don't know what to think of the infected
apartment building.  So far it has only happened once.  How often
should we expect it?

If we ignore the erratic Chinese reporting and the infected
apartment building by starting with April 2, we have 2671 cases on
April 8 and 2223 cases on April 2, which works out to 3.1% per day, or
a doubling time of 22.6 days.

The outcome probably depends more on the unknowns than the knowns.
The unknowns I can see are:

   the mutation rate of the virus, 
   how hard it is for it to mutate and become more virulent, 
   how long it will take to make a vaccine, 
   how often to expect infected apartment buildings, 
   whether it can really be transmitted by cockroaches, and
   what regions have the disease but aren't filing reports with the WHO.

Neither do I know when the medical facilities in Hong Kong will get
overrun to the extent that they can't quarantine new cases.  However
this last one seems at least knowable.

Tim Freeman                                                  
Which is worse: ignorance or apathy? Who knows? Who cares?
GPG public key fingerprint ECDF 46F8 3B80 BB9E 575D  7180 76DF FE00 34B1 5C78 

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