Antibody Test Steps:
Also known As SARS-Cov-2 AB test checks for presence of antibodies to coronavirus in the blood.
Antibody test is very different from molecular covid19 test, which is done with nasal swab, and is checking for presence of the covid-19 virus itself.
Antibodies are produced by immune system approximately 10 days after onset of the infection and remain positive long after the infection.
This is why antibody test can be used to detect a past infection with coronavirus.
AllCare is offering antibody test to asymptomatic (not exhibiting any signs or symptoms of active infection) patients only.
If you have mild cough or runny nose or still recovering - we have to wait 7 days after you recover completely in order to get this test.
We cannot accommodate any sick visits for covid19 (sars-cov-2) antibody blood test at this time.
For above mentioned reasons, all patients will need to consult an AllCare physician via telemedicine or in-person before they can be considered for covid-19 antibody tests.
Also, if you are already in our office for completely different reasons, we can offer you to get this test done on-the-spot.
AllCare offers the blood test to asymptomatic patients at ANY of our locations.
Prior to your blood draw you need a consultation with our doctor.
Doctor will make sure you are 7 days asymptomatic at the time of the blood draw.
Doctor will also document the timing and nature of your past symptoms (if any).
Last, but not least, doctor will counsel you on limitation of the test and interpretation of results.
Expected turnaround time today is 1-3 business days.
Since the test is very new, this may change with time.
As usually done at AllCare, we will email and text you as soon as we have seen/interpreted your results!
The answer is NO!
There are currently NO "FDA approved" SAR-Cov2 antibody tests available.
Several assays have "Emergency Use Authorization (EUA)" which is not the same as "FDA Approved".
These FDA EUA tests very in their performance characteristics widely. Please refer to charts below for more info.
In the phase 1 (11 day prevalence study) we utilized LabCorp's ELISA assay for three SARS-COV-2 antibody bands: IgG, IgM and IgA.
IgG turns positive within 7-20 days of infection and tends to persist for over 6months (likely years).
IgM turns positive within 7-20 days of infection onset, peaks @ 80 days and fades away within 6months.
IgA from limited data available we assume it should follow the same course as IgM.
Upon reviewing our phase 1 testing results* (4/28/20, read below for more details) we concluded that IgM and IgA assays produce too many false positives and false negatives.
Therefore, in phase 2 of the testing (precision PPV focused testing) - we will only order IgG / total antibody assays.
In phase 2 of our testing (after 4/28/2020) we will be using 2 different FDA "emergency use authorized" assays: Ortho and Abbott (performance review available below).
The answer is NO! Not yet Anyway. First we have to make sure it isn't falsely positive.
Our doctors will counsel your on what they mean
In an ideal world we can have a test that is never wrong. Let's take a crash course on different test specs and later examine what implications these have on covid-19 pandemic:
Sensitivity is the ability of the test to find the cases.
Simplified & COVIDified: If tests is given to 100 people infected with the virus - how many will come back positive?
Specificity is the abillity of the test to find the controls.
Simplified & COVIDified: If tests is given to 100 people who never got the virus - how many will come back negative?
Positive Predictive Value (PPV)
Simplified & Covidified: If I tests positive- what are the chances that I had the virus (vs. lab error)?
Negative Predictive Value (NPV)
Simplified & Covidified: If I tests negative- what are the chances that I did not have the virus (vs. test failed to detect it)?
First FDA first Emergency Use Authorizations (FDA EUA) was granted 4/1/2020 to a 15minute, Point-Of-Care (P-O-C) test from Cellex.
As of 5/5/2020, we have total of three FDA EUA P-O-C tests, all three lacking specificity, effectively rendering themselves useless for most of USA where prevalence is thought to be low (<10%).
The table below explains why our patients should refrain from any 15minute P-O-C antibody tests, and why AllCare is using only laboratory assays from certain manufacturers.
Figure #1: Practical Value Of All FDA EUA antibody tests in different US regions.
Explanation for 3 prevalence scenarios:
1% prevalence - most of the country today.
10% prevalence - hotspots & clinical settings.
33% prevalence - NYC for most of 2020:
Figure #2: Details of NPV PPV calculations for latest 15minute Point-Of-Care tests authorized by FDA.