Saturday, May 2, 2009

Too soon to say

Suddenly, stories like this one abound, implying that the outbreak of H1N1 Swine Flu may not be such a big deal after all.

Of course, we all hope it turns out not to be a big deal, but as they finally got around to mentioning in paragraph 5 of the new article, it's "...too soon to be certain what the swine flu virus will do."

We are so early in this outbreak that we really don't know much about the epidemiology of this virus at all.  
  • How many people have the disease?
  • How many people have died?
  • How readily is it transmitted from person to person?  
  • What risk factors are there for infection (does it spread well among people crammed into the same airplane for several hours, but poorly in more open settings; are smokers or the elderly or some other group more likely to catch it)?  
  • How lethal is the virus to those who catch it?  
  • Who is most at risk of severe disease?
  • When it does kill people, is it the flu infection itself (primary viral pneumonia) that causes death or is it secondary bacterial pneumonia that moves in after the flu virus is gone?
And it will be awhile before we have many of the answers.  In the UK, they are waiting for the results of more than 600 tests for the virus.  Mexico has a backlog of over 35,000 samples waiting to be tested, and their total number of confirmed cases shot up by nearly 250 overnight to 397 as a result of additional testing (not necessarily correlated to any new cases).  In the US, it's taking 4 days to get test results, which -with a virus that has only a 24 to 96-hour incubation period- means that our picture of confirmed cases here at home is far behind the times, as well.

And all that only goes to the epidemiological situation now.  The situation is likely to change over time, as the virus mutates.  In the case of the 1918 Pandemic, for instance, the first wave of infections spread around the world in the spring, and it was pretty mild.  It wasn't until the fall, when the next wave of infections struck, that the virus became so frighteningly lethal.

So I'm very pleased that the CDC, the Department of Health and Human Services, and the Department of Homeland Security are all continuing to take the situation very seriously and are doing an excellent job of letting the public know what we do and don't know.  

Dr. Besser, Acting Director of the CDC, has done a particularly good job of communicating the expectation that the government's response, the guidance to the public and the guidance to healthcare professionals will all continue to change as the situation evolves --and that that's a good thing. 

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