The question isn’t how many people have been infected since the beginning of the pandemic. The question is: how many are currently infected by the virus, currently carrying active virus inside their bodies?
On average, a person infected with covid remains infected for 2 weeks. So the total number of infected people on any given day is the sum of those who have been newly infected each day for the prior 14 days.
The daily covid death count is the most accurate indicator of the spread of the virus. However, deaths lag behind infections by about three weeks; i.e., the average person who dies from covid was infected 3 weeks prior to dying.
Somewhere around 0.65 percent of those who’ve been infected with covid eventually die from the disease. So, divide the most recent 14-day death count by .0065 to estimate the number of people infected 21 days ago.
The daily case count in the US underestimates the daily infections. However, over the past month the change in daily case counts has fairly accurately mapped onto the change in estimated daily infections.
Over the past two weeks, November 6-20, 18,100 Americans died of covid. So, as of three weeks ago, there would have been 18,100/.0065 = 2.8 million Americans actively infected by the virus.
Over the past two weeks (11/6 – 11/20), the 14-day total new case count was 2,212K. Three weeks prior (10/15 – 10/29) the 14-day total new case count was 992K. So, the current case count is 2212/992 = 2.23 times what it was two weeks ago. Assuming proportionality of changes in case counts to changes in new infections, then the total number of infected people today is 2.23 times the number of people who were infected three weeks ago.
2.8 million infected 3 weeks ago x 2.23 = 6.24 million Americans are currently infected by covid.
The total US population is 328 million. 6.24/328 = 0.019. So, about two percent of the American population is currently infected by live covid virus.