# Another Numbers Post (and a correction)

First, I would like to make a correction to the U.S. infection rate numbers I put in my last post.  I made a mistake in the way I built my equation for calculating infection rate.*  My apologies for reporting improperly calculated numbers!  Here is the corrected and updated graph of U.S. infection rates for the last three and a half weeks. vs day. From March 17-21 the U.S. infection rate DID get above the 33% infection rate seen in Italy, but not as much as I said in my last post.  As a country during that period our infection rate averaged 42%, with a high of 49% on March 19.  Since then, our infection rate has steadily dropped and is now at about 13%.

The U.S. reported around 33,000 new infections on April 4th, which is quite a large number, yet it is just a 12% increase over the April 3rd numbers.  If our infection rates were still at 42%, we would have had 116,000 new infections on April 4th.  We are in fact moving in the right direction.  But trying to stop a pandemic is like trying to stop a speeding train.  We have slowed the train’s acceleration, but it is still speeding up, with a lot of momentum behind it.  Remember, it takes upwards of three weeks for a person with this infection to fully recover, and 187,000 of our current infections occurred in the last week alone.  If we continue to hold at a 12% infection rate, in the next week we will see about 300,000 new infections.  In the following week, maybe 800,000 new infections or more.  If those 187,000 who were infected last week all recover, in two weeks we will still have almost a million people who are coronavirus-positive in the country, each potentially spreading the virus to others.

The only way for these numbers to finally drop is if more people recover each day than the number of new infections, and that won’t happen unless we can bring the infection rate to near zero.  The ideal way to bring an infection rate to a standstill is to vaccinate a large majority of the population against the disease.  This option isn’t available to us yet.  For now, our only effective tool in fighting this virus is to change our own behavior in order to block it from continuing to spread.  Because the virus can be passed by people who are asymptomatic, the best way to prevent new infections is for each of us to behave as if we are already infected, even if we feel completely well, and to do everything within our power to keep that infection to ourselves.  Rather than fighting off a zombie invasion, we must think of ourselves as the zombies, and our main goal is to NOT make new zombies.  This is a group effort on par with the war effort of WWII, but very different in one fundamental way: instead of gathering together to defeat another people, we must work apart, but as one, to help save each other.  If this virus were to sweep across the whole world before a vaccine is developed, it could cause at least as many deaths as WWII.**

* Rather than having Excel subtract yesterday’s numbers from today’s numbers and then divide by yesterday’s total, I was dividing by the number of infections my original model of 33% growth had predicted for that day (I had selected the wrong cell)

**  I took the global population demographics (number of people in each age group, https://population.un.org/wpp/DataQuery/) and multiplied that by the observed fatality rates for each age group (https://www.worldometers.info/coronavirus/coronavirus-age-sex-demographics/).  Assuming everyone on the planet caught this virus, and the eventual fatality rates were the same as what we’ve seen so far, we could expect about 87 million deaths, globally, mostly in those who are 50 years old or older.  While the real number would probably be lower due to asymptomatic infections, people who are over 50 are increasingly less likely with increasing age to be infected and asymptomatic, and so I would expect this number to not be too much of an overestimate.