After 2 weeks of information overload from the news channels on “antibody” tests for Covid19, the general public seems to be newly educated on the difference between the virus test and the antibody test. This is reminiscent of those of us who were watching the Gulf War live on CNN in 1990-1991 and learned details about Tomahawk Cruise missiles; things I never thought I would have to care about.
Since my article was originally posted on April 7, 2020 in the Community Newspapers describing the difference between antibody testing and virus testing, I received many emails from people who themselves had tested positively for the Covid19 virus and wanted to know where they can get the antibody test, believing they might find out if they were immune.
There are certainly differing opinions on this and the value of these rapid antibody tests. People who have taken the PCR (virus) test for Covid19 and tested positive and were retested later with a negative virus result would love to know if they are ‘immune’. Now, there is new anecdotal evidence that a person is not necessarily immune just because they previously had the Covid19 virus. What should these people be told about taking the test?
The first important decision point should be what the does the FDA and CDC have to say about rapid antibody testing. The FDA has not “approved” a single antibody test for Covid19 as of April 25, however, they have “authorized” use of the following antibody tests.
4/01/2020 – Cellex
4/14/2020 – OrthoClinical and Chembio
4/15/2020 – Mount Sinai (IgG only)
4/24/2020 – Autobio Diag
4/24/2020 – DiaSorin & OrthoClinical (both IgG only)
But are these authorized tests being authorized based on the manufacturer/lab producing their own documentation of evidence/verification ? Isn’t this the fox watching the hen house? I would advise people to read the FDA web site and come to their own conclusions on what “authorization” really means before relying on results from rapid antibody tests.
In Miami-Dade County the random antibody testing conducted over the last 3 weeks used a different brand of test from the 7 listed above. Apparently, those tests were not approved or authorized by the FDA; not surprising given the Cellex test was the only one FDA authorized as of April 6th when the County’s testing begun and perhaps not available in quantity for the County to purchase.
Based on the test results from Dade County’s rapid antibody testing, they concluded the following; 60% of all people who tested positive for antibodies were “asymptomatic” meaning they did not show symptoms of the virus. Secondly, there had been closer to 165,000 cases of Covid19 in Dade County than the Florida State Department of Health’s statistic which showed there had been about 10,700 confirmed cases of Covid19. This implies the Florida DOH figure was understated by a factor of more than 15x.
Should the County use those statistics to aid them in their decision to start opening facilities and businesses in Dade County? As a concerned resident and as Vice Mayor of my City, Palmetto Bay, responsible for deciding to accept County executive orders or apply more restrictive versions by our City, I would like to see the published results of the tests along with any correlating evidence to verify accuracy. Questions for these unapproved tests should be;
Was there a control/accuracy test done by the County at any point to find people in the random testing who they knew were previously infected and recovered (based on PCR tests)? If they at least asked that question and had those statistics, and the data correlated reasonably well, some level of accuracy could be validated.
Alternatively, did they take a few dozen of one of the FDA approved test kits, like Cellex, and instead of taking one drop of blood after the finger prick, take two and put one in each of the test kits side by side to insure at least 60-80% of the results are identical ? If the County did that and the results were significantly different, that might mean the two different test kits are measuring a different range, sensitivity or type of antibody. This is common sense, but how much common sense was applied in the County’s random antibody test program and to the use/publishing of results? We as residents of Dade County deserve to know, and the County Commission should audit these results to validate policy decisions that could have a potentially fatal outcome for some of us.
Finally, why are some of the most recent FDA “authorized” tests from the big name medical facilities like Mt Sinai only doing IgG antibody testing instead of both IgM and IgG? Refer to the April 7th article in the Community Newspapers, [link], for a simplistic explanation of IgM and IgG. After OrthoClinical got FDA authorization for IgM/IgG test kit on 4/14, why did they subsequently get approval for a different antibody test on 4/24 that only does IgG? Why did Pitkin County, according to the Post Independent, the main multi-county newspaper in Glenwood/Eagle/Pitkin County Colorado, have a headline a few days ago stating; “Pitkin County’s COVID-19 antibody test plan shelved over accuracy questions”?
If I previously had the virus, I too would want to know the results of an antibody test. However, knowing what we know or don’t know at this point, I would probably wait until there is more proven accuracy for these rapid antibody tests or ideally, until there is an FDA approved test. If not, I wouldn’t consider the results of these tests conclusive or actionable.