How Many Americans Currently Have the Virus?

  • Per IHME, the covid modeling outfit at the U. of Washington: Daily deaths is the best indicator of the progression of the pandemic, although there is generally a 17-21 day lag between infection and deaths… For estimated infections, we start with death estimates, then work backward, using infection fatality ratios to estimate infections based on deaths.
  • IHME uses an infection fatality ratio of around 0.85%. So, for every person who dies of covid, there have been around 1/.0085 = 118 people who’ve been infected.
  • Per CDC and WHO, people who’ve been infected remain contagious for around 10 days on average.
  • Over the 10-day interval from August 20-30, 9,234 Americans died of covid. 9,234 deaths x 118 infections per death = 1.1 million people in the US were infected and contagious during the 10-day interval from around August 3-13. The death rate has been pretty steady for most of August, so assume 1.1 million Americans are currently infected and contagious.
  • Population of the US = 328 million. 1.1M/328M = 0.34% currently infected and contagious in the US.
That doesn’t seem like a high prevalence. But assuming a steady state of epidemic contagion, within ten days the 1.1 million people currently infected will pass the virus on to another 1.1 million before recovering (or dying), and so on. As of the end of August, 6.7 percent of Americans have been infected since the beginning of the epidemic. By the end of September it’ll be 7.7 percent; by the end of November, 8.7 percent…

 

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