H1N1: Do We Know How Many People Have Been Infected?

Blog Post — November 18, 2009

Stephen Morrison and Phillip Nieburg of CSIS recently co-authored a piece on uncertainties surrounding the H1N1 vaccine supply and President Obama’s decision to declare H1N1 a national emergency. The post produced many questions about vaccines and highlighted much of the confusion surrounding the flurry of information from health experts, government agencies and various news outlets.

Comment from the blog:

Schools are closing, parents are terrified, and much of this is being fueled by the fact the quality of reporting on 24 hour news stations is alarmist and detached from reality. Interviews are being given to random opinionated individuals with an "MD" by their name in favor of credited public health and influenza experts.

Should we be concerned that we aren't even trying to effectively track this disease? What you're saying is that numerical projections are completely bogus so any number spewed out to the population, in the thousands or millions, is a shot in the dark and heavily subject to political manipulation and sensational media. If hospitals aren't even testing for H1N1 on a large scale, how does Thomas Frieden presume to make any estimation at all?

Meanwhile, the Obama Administration will cover its tracks by declaring a national emergency because they are fearful of being viewed as unresponsive in an increasingly treacherous political climate of declining public support and accusations of ineffectiveness.

Americans are just looking for honesty. What are the actual projections for this disease? How bad is it really? Should parents be pulling their children out of school in droves? Should we be investing in protective masks for our families? Beyond washing our hands and avoiding public places while sick, are there any other preventative measures U.S. citizens can take?

Response from Phillip Nieburg:

The commenter is correct about the sometimes unhelpful quality of media reporting about H1N1, including the comments of people with limited understanding of disease surveillance and of public health in general.

Regarding the decision of the Centers for Disease Control and Prevention (CDC) to stop trying to count every person infected with H1N1, influenza is a disease with a wide spectrum of severity, from mild “cold” symptoms that do not include fever to overwhelming pneumonia and death. Once the existence of an influenza epidemic has been confirmed, as it has in this situation, the goal of influenza surveillance shifts from counting every infected person to gathering information on the severity and impact of disease. These latter data can better help guide decisions about the subsequent public health response. At this point, since infected people in the U.S. may ultimately number in the tens of millions, and since many mildly infected people with mild disease will not seek medical attention, and since confirming an H1N1 diagnosis requires an expensive laboratory test, it no longer makes sense to try to count every person infected with H1N1.

However, although the CDC has stopped counting every individual H1N1 infection, it is keeping close track of – and is making publicly available on a weekly basis - a number of other measures of epidemic influenza severity in the United States: (1) visits to doctors for influenza-like illness; (2) total influenza-related hospitalizations; (3) the proportions of weekly deaths recorded as being from pneumonia and influenza; (4) state health department estimates of the magnitude of influenza activity within each state; (5) the numbers and proportions of influenza viruses identified in laboratories as H1N1 viruses; (6) any resistance of circulating H1N1 viruses to oseltamivir, the principal anti-viral drug being recommended for high risk people infected with H1N1; and (7) influenza-associated pediatric mortality. Each of these disease indices is updated weekly and can be found online.

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