Centers for Disease Control and Prevention (CDC), updated 30 June 2020 - Test for Past Infection (Antibody Test) - What do your results mean? If you test positive / If you test negative

Test for Past Infection (Antibody Test)
- What do your results mean? If you test positive / If you test negative
 
Published by:
Centers for Disease Control and Prevention (CDC), updated 30 June 2020
https://www.cdc.gov/coronavirus/2019-ncov/testing/serology-overview.html
 
From the article:
 
What do your results mean? If you test positive
* A positive test result shows you may have antibodies from an infection with the virus that causes COVID-19. However, there is a chance a positive result means that you have antibodies from an infection with a virus from the same family of viruses (called coronaviruses), such as the one that causes the common cold.
* Having antibodies to the virus that causes COVID-19 may provide protection from getting infected with the virus again. If it does, we do not know how much protection the antibodies may provide or how long this protection may last.
* Talk with your healthcare provider about your test result and the type of test you took to understand what your result means. Your provider may suggest you take a second type of antibody test to see if the first test was accurate.
* You should continue to protect yourself and others since you could get infected with the virus again.
   > If you work in a job where you wear personal protective equipment (PPE), continue wearing PPE.
* You may test positive for antibodies even if you have never had symptoms of COVID-19. This can happen if you had an infection without symptoms, which is called an asymptomatic infection.
 
What do your results mean? If you test negative
* You may not have ever had COVID-19. Talk with your healthcare provider about your test result and the type of test you took to understand what your result means.
* You could still have a current infection.
   > The test may be negative because it typically takes 1–3 weeks after infection for your body to make antibodies. It’s possible you could still get sick if you have been exposed to the virus recently. This means you could still spread the virus.
   > Some people may take even longer to develop antibodies, and some people who are infected may not ever develop antibodies.
* If you get symptoms after the antibody test, you might need another test called a viral test​.
 
Regardless of whether you test positive or negative, the results do not confirm whether or not you are able to spread the virus that causes COVID-19. Until we know more, continue to take steps to protect yourself and others.

medRxiv, 5 June 2020 - Are antibodies tests accurate? Understanding predictive values and uncertainty of serology tests for the novel coronavirus [by Naomi C Brownstein & Yian A Chen]

Title:
Are antibodies tests accurate? Understanding predictive values and uncertainty of serology tests for the novel coronavirus.

Authors:
Naomi C Brownstein & Yian A Chen

Published:
medRxiv, 5 June 2020
[Keep in mind that this article is a preprint and not yet peer reviewed.]
https://www.medrxiv.org/content/10.1101/2020.06.04.20122358v1

Abstract:
Antibodies testing in the coronavirus era is frequently promoted, but the underlying statistics behind their validation has come under more scrutiny in recent weeks. We provide calculations, interpretations, and plots of positive and negative predictive values under a variety of scenarios. Prevalence, sensitivity, and specificity are estimated within ranges of values from researchers and antibodies manufacturers. Illustrative examples are highlighted, and interactive plots are provided in the Supplementary Material. Implications are discussed for society overall and across diverse locations with different levels of disease burden. Specifically, the proportion of positive serology tests that are false can differ drastically from up to 3% to 88% for people from different places with different proportions of infected people in the populations while the false negative rate is typically under 10%.

bioRxiv, 3 June 2020 - Brief Communication: Magnetic Immuno-Detection of SARS-CoV-2 specific Antibodies

Title:
Brief Communication: Magnetic Immuno-Detection of SARS-CoV-2 specific Antibodies

Authors:
Jan Pietschmann, Nadja Voepel, Holger Spiegel, Hans-Joachim Krause & Florian Schroeper

Published:
bioRxiv, 3 June 2020
[Keep in mind that this article is a preprint and not yet peer-reviewed.]
https://www.biorxiv.org/content/10.1101/2020.06.02.131102v1

Abstract:
"SARS-CoV-2 causes ongoing infections worldwide, and identifying people with immunity is becoming increasingly important. Available point-of-care diagnostic systems as lateral flow assays have high potential for fast and easy on-site antibody testing but are lacking specificity, sensitivity or possibility for quantitative measurements. Here, a new point-of-care approach for SARS CoV 2 specific antibody detection in human serum based on magnetic immuno-detection is described and compared to standard ELISA. For magnetic immuno-detection, immunofiltration columns were coated with a SARS-CoV-2 spike protein peptide. SARS CoV 2 peptide reactive antibodies, spiked at different concentrations into PBS and human serum, were rinsed through immunofiltration columns. Specific antibodies were retained within the IFC and labelled with an isotype specific biotinylated antibody. Streptavidin-functionalized magnetic nanoparticles were applied to label the secondary antibodies. Enriched magnetic nanoparticles were then detected by means of frequency magnetic mixing detection technology, using a portable magnetic read-out device. Measuring signals corresponded to the amount of SARS CoV 2 specific antibodies in the sample. Our preliminary magnetic immuno-detection setup resulted in a higher sensitivity and broader detection range and was four times faster than ELISA. Further optimizations could reduce assay times to that of a typical lateral flow assay, enabling a fast and easy approach, well suited for point-of-care measurements without expensive lab equipment."

International Business Times, 4 May 2020 - Coronavirus Antibody Test With 100% Accuracy Gets FDA Approval, Step Closer To COVID-19 Immunity

Title:
Coronavirus Antibody Test With 100% Accuracy Gets FDA Approval, Step Closer To COVID-19 Immunity

Author:
Arthur Villasanta

Published:
International Business Times, 4 May 2020

Key points:
* The U.S. FDA has granted emergency use approval to an antibody test with 100% accuracy developed by Roche 
* The test is called Elecsys Anti-SARS-CoV-2 
* It uses IV blood draws and not finger-prick assays

To read thia article:
https://www.ibtimes.com/coronavirus-antibody-test-100-accuracy-gets-fda-approval-step-closer-covid-19-2969643

Scholarly Article (The Lancet, 27 April 2020) - What policy makers need to know about COVID-19 protective immunity.

Title:
What policy makers need to know about COVID-19 protective immunity

Authors:
Daniel M. Altmann, Daniel C. Douek & Rosemary J. Boyton

Published:
The Lancet, 27 April 2020
Available: https://www.thelancet.com/journals/lancet/article/PIIS0140-6736(20)30985-5/fulltext

From the article:
"About a third of the world is under lockdown as a public health measure to curb the spread of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the virus that causes coronavirus disease 2019 (COVID-19). Policy makers are increasingly pressed to articulate their rationales and strategies for moving out of lockdown; the process of re-emergence is already cautiously starting in Austria, Switzerland, Denmark, Wuhan, and some US states. As the counterpoise between further disease spread and socioeconomic costs is debated, it is essential that policy makers in all affected countries have the best possible data and understanding to inform any course of action."