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Results of random Covid-19 testing in Indiana

July 29, 2020

In response to the unending complaints** that we just aren’t carrying enough Covid-19 pandemic information to suit your unquenchable thirst for the grim truth, we offer this synopsis of a recent study, the subject of an article in The Conversation (motto: Academic rigor, journalistic flair), which frequently has well-written articles of great interest (to me, anyway).
[Chuck Almdale]

** (I wish.)

Random testing in Indiana shows COVID-19 is 6 times deadlier than flu, and 2.8% of the state has been infected

By Nir Menachemi, Professor of Health Policy and Management, IUPUI
The Conversation |  July 21, 2000

The beginning of the article:

Since day one of the coronavirus pandemic, the U.S. has not had enough tests. Faced with this shortage, medical professionals used what tests they had on people with the worst symptoms or whose occupations put them at high risk for infection. People who were less sick or asymptomatic did not get tested. Because of this, many infected people in the U.S. have not been tested, and much of the information public health officials have about the spread and deadliness of the virus does not provide a complete picture.

Short of testing every person in the U.S., the best way to get accurate data on who and how many people have been infected with the coronavirus is to test randomly.

I am a professor of health policy and management at Indiana University, and random testing is exactly what we did in my state. From April 25 to May 1, our team randomly selected and tested thousands of Indiana residents, no matter if they’d been sick or not. From this testing we were able to get some of the first truly representative data on coronavirus infection rates at a state level.

We found that 2.8% of the state’s population had been infected with SARS–CoV–2. We also found that minority communities – especially Hispanic communities – have been hit much harder by the virus. With this representative data, we were also able to calculate out just how deadly the virus really is.

A summary of the findings:

  • Date of Study: April 25 – May 1, 2020
  • Study Size: 3600 randomly selected, 900 open testing volunteers
  • Population of Indiana, 2020, estimated: 6,732,329
  • Test sites: 70 testing stations in cities and towns across Indiana
  • Tested with: PCR swabs for current infections, antibody blood test for past infections
  • Infections found: 1.7% had active viral infection, 1.1% had antibodies from past infections
  • Infection rate: 2.8% with 95% confidence actual rate is between 2% and 3.7%
  • Known Indiana Covid-19 cases & deaths 4/29/20: 17,756 cases, 1109 deaths. (Wikipedia)
  • Estimated 4/29/20 actual cases vs. known cases: 188,000 vs 17,756, or 10.6 times higher
  • Death rate of known cases: 1,109 / 17,756 = 6.25%
  • Death rate of estimated cases: 1,109 / 188,000 = 0.58%, or 9% of above death rate
  • Death rate of 0.58% is approximately 6 times higher than 0.1% typical flu death rate
  • 44% of those who tested positive for active viral infection reported no symptoms
  • Infection rates in minority communities are higher; the rate for Hispanics is about 8%. This is likely because Hispanics are more likely to be essential workers and live in extended family structures
  • People living with an infected person are 12 times more likely to have the virus than people not living with an infected person
  • The low 2.8% overall infection rate combined with the much higher rates for those living with infected people or in extended families indicate that social distancing actually does work.

Some conclusions:

  • When authorities focus on testing the symptomatic and don’t do random testing, the actual rate of infection is likely to be 10 times higher than the confirmed (known) rate.
  • As of Sunday, 7/26/20, Los Angeles County reported 176,028 cases and 4,375 deaths, for deaths per known case rate of 2.5%. If the deaths per actual cases rate found in the Indiana study of 0.58% is accurate, we have 754,000 cases of infection, but we don’t know who 578,000 of them are.
  • Similarly, for 7/26/20, California reported 460,550 cases and 8,445 deaths, for deaths per confirmed case rate of 1.8%. Using the Indiana study death rate of 0.58%, we have 1,456,000 cases of infection and we don’t know who 996,000 of them are.
  • 44% of the currently Covid-19 infected have no symptoms. This agrees with the 40% – 50% range reported in many other areas.
  • The good news is that Covid-19 is 1/2 to 1/12th as lethal than previously thought. The bad news is that if you are old with preexisting conditions, an essential worker, live in an extended family structure, or avoid masks and social distancing, you’re more likely to sicken and/or die.
  • When 2.8% of the population was infected (3 months ago), 97.2% were not, thus there was an enormous pool of waiting-to-be-infected. This pool has shrunk, but it’s still huge. Wave 2.0 could be huge (we’re still in wave 1.5).
  • If you don’t live in Los Angeles or California, find out your area numbers and apply the percentages found in the study. The key numbers are: 2.8% overall infection rate, 0.58% actual case death rate, 44% of infected (thus potentially infectious) have no symptoms.  Also: read the article.

 

 

 

 

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