Coronavirus Antibodies and Covid19 Immunity
Establish baseline prevalence and best Sars-cov-2 Antibody Test (Completed 4/28/20)
Precision Antibody / Immunity Testing For Individuals
Monthly Report On Progress Toward Herd Immunity
Keep Calm & Get Covid19 Antibody Tested!
The AllCare Family Medicine & Urgent Care has, again, stepped up in the fight against Covid-19 pandemic.
We are the first physician group in MidAtlantic region to offer a Covid-19 blood antibody test in partnership with LabCorp.
Does Having Covid-19 Antibody(ies) Mean Immunity?
The answer is NO!
Not yet, anyway. First we need to make sure that the individual test result isn't falsely positive. This may be due to a lab error (mislabeled specimen for example) or cross-reactivity with other non-sars-cov2 coronavirus antibodies. Secondly, the assumption that you cannot get covid-19 twice is a best scientific guess and not a proven fact yet.
Prevalence of COVID-19
This blood test is currently of utmost importance in estimating the prevalence of COVID-19 in the general US population. By testing the presence of antibodies, we will have a better understanding of approximately what percentage of the population has already been SARS-Cov2 infected and has recovered. This information is vital to our public for both prediction of herd immunity development, as well as validation and interpretation of future serological tests.
Herd Immunity to COVID-19
We need population level antibody information (seroprevalence) in order to predict just when herd immunity may develop. Generally speaking 60% of population being immune to the virus will act as a human firewall slowing or stopping the virus from effectively spreading to the remaining of 40% of the population that is still susceptible. Actual numbers of course depend on how virulent this virus is.
Individual Immunity to COVID-19
Once more data on accuracy of the antibody tests are available, these blood tests can also be used to identify individuals who have developed immunity to COVID-19, thus allowing them to return to their business as usual. This will be a key facilitator of the gradual re-opening of our country and return to normalcy.
How Do I Get My Coronavirus Blood Test?
AllCare's covid-19 nasal swab test is reserved for symptomatic individuals and is carried out in drive-thru fashion to limit the spread.
In contrast, the covid-19 blood antibody test (serology) is best suited for asymptomatic individuals (>10 days without any symptoms) who may have already had the virus without knowing it or have had the virus but did not have access to testing at that time.
Hence, blood test will be available in-office after a either telemedicine or in-person consultation with one of AllCare's doctors.
Doctors will be documenting the timing of suspected symptoms and exposure and more importantly counselling patients on interpretation of the upcoming results.
The blood test is checking for presence IgG band of SARS-Cov2 antibodies(Abbott) or total antibody (Ortho). As early adopters, we will help our patients in interpreting the results.
Making a false impression that someone is immune to covid-19 will be very dangerous because it may alter their behavior and expose them to the Covid-19.
The Devil In The Details: Covid-19 IgG IgM Testing:
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 abillity 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
Simplified & Covidified: If I tests positive- what are the chances that I had the virus (vs. lab error)?
Negative Predictive Value
Simplified & Covidified: If I tests negative- what are the chances that I did not have the virus (vs. test failed to detect it)?
Let us examine a hypothetical ideal test and how it would perform in USA general population:
Did You Notice?:
Positive Predictive Value for the same exact test varies from virtually useless/dangerous to very helpful, depending on how many people have had the virus in the population being tested (Prevalence).
In many cases, because of false positives, we will not be able to tell whether particular individual has recovered from covid19 and has developed antibodies / immunity or not. Yet we certainly will be able to see what percentage of people in our general population have fought covid-19 and built antibodies to it (prevalence).
This is why AllCare and all of our patients, as an early adopters of this technology, on 4/28/20 have completed a 11 days prevalence study, in order to able to give everyone a better certainty on what tests results mean and where we stand on the progress of the herd immunity.