*This story was updated on April 26, 2020
There is much misunderstanding about the testing for the Covid-19 Corona Virus due to an overwhelming amount of misinformation and misperceptions of testing and the meaning of the test results. This document should help to clarify testing and educate the public on what Miami-Dade County is doing with Covid-19 testing announced by County Mayor Gimenez on Friday, April 3rd, 2020 and what Camillus Health concern is doing about testing the homeless population in Dade County.
Types of Test
There are two types of tests that are being conducted for Covid-19; one is a test of whether someone is infected with the Virus, this is called the PCR test. The other is an antibody test to see if a person has developed antibodies in their blood to fight the virus.
RT-PCR test (Reverse Transcription – Polymerase Chain Reaction)
This is a test whereby a trained clinician/tech gets a swap from your respiratory system (saliva/mucus from mouth typically) and sends the sample to a certified lab for evaluation to see if it tests positive for the Covid-19 virus. Unfortunately, this can take from 3-10 days for a PCR tests as of early April 2020.
Antibody Test IgM & IgG (Immunoglobulin M & G)
This is a test to see if a person’s immune system has created an antibody in the blood stream (protein) to fight the virus. There is a 15-minute or less test done to determine if you test positive for Covid-19 IgM and IgG antibodies. The particular antibody test being used by Dade County and Camillus Health are done by pricking your finger like a blood sugar test and providing outcomes.
The test is supposed to tell you if you have an early stage antibody for Covid-19 meaning you were infected with virus at least 3-5 days earlier (test shows IgM + and IgG -). It also identifies a later stage persistent antibody for the virus, the IgG. An IgM- and IgG+ is believed to mean you had it but are no longer infected with it and potentially immune from Covid-19. Most of the rapid antibody test manufacturers publish the expected false negative results to be between 7-13% or so.
The 20,000 Dade County 15-Minute Antibody Tests
The County Mayor, Carlos Gimenez, has ordered 750 of these tests to be conducted each week starting Monday, April 6, 2020. Although the tests will NOT necessarily help determine the number people currently infected with the virus on a given day, it has tremendous value in determining the scariest part of the Covid-19 pandemic; the denominator in the equation that will give us the first views into the real percentage of infected people who will experience serious illness or death.
In theory, the county needs to administer roughly 384 of these tests to have a 95% confidence across the millions of people living in Dade County and 1038 tests to get a 97% confidence on the denominator. However, since the county is conducting these tests randomly within categories; the categories are as follows; Geographical (32 municipalities/regions), gender, race and 3 age groups (18-40, 41-64, and 65 and older). Therefore, they will likely need 384 and 1038, respectively, within each category to get the desired results of 95% or 97% accuracy.
County Method for Testing
Dade County is administering their tests at 10 library sites throughout the county. Each test site has a tent provided by UM with 2-3 Emergency Services persons (EMS/firefighter), 1-2 medical professionals from UM and 1 police officer).
Camillus Health Concern
It is imperative for the Homeless Population to be tested as they typically congregate and have some of the highest average levels unhealthiness (diabetes, hypertension, auto-immune deficiency, etc.) that significantly increases the likelihood that one infected with Covid-19 will transition from asymptomatic or mild symptoms to serious illness or death.
Camillus Health Concern also received a donation of 2,000 of the same antibody test kits from Matt Wideman of the Love and Life Foundation. Camillus Health will be taking some percentage of these kits and follow the same protocol as the County in terms of conducting random testing of the homeless population; probably using separate categories only for the 3 age groups and gender. The number of tests per category will be much lower to achieve 95% or 97% confidence levels.
Camillus Health will be working together with all the stakeholders for the homeless population including the Homeless Trust, Camillus House, UM and others to determine appropriate testing for both the homeless people and the clinicians involved.
The statistics compiled by Camillus Health will be helpful, especially compared side by side to the results of the County’s testing to determine if homeless people throughout the nation will be at significantly higher infection levels and the associated risk of spreading the virus. This should probably be done for the prison populations and other higher risk groups within society. Once that is determined, a more comprehensive and effective plan can be put in place to deal with isolation/quarantine for Americans who do not have the means to do so themselves.
John DuBois is the Chairman, Camillus Health Concern. John can be reached at JohnD@CamillusHealth.org