Whether by nasal swab or finger prick, testing for the novel coronavirus has become available to the public in a few different ways since the pandemics outbreak.

According to the Centers for Disease Control and Prevention, samples must be taken from the upper respiratory system, such as through a nasal or throat swab, and sent to laboratories to be analyzed in order to properly diagnose a person for COVID-19. This form of testing is also known as molecular testing.

The other type of coronavirus testing, known as serology or antibody testing, does not diagnose for COVID-19, as recommended by the CDC. However, officials said it can detect a previous coronavirus infection and contribute to research to give health care providers a better understanding of the ongoing pandemic.

What is serology (antibody) testing?

Serology testing, also known as antibody testing, uses a small blood sample taken by finger prick to test for the presence of antibodies created in response to COVID-19 infection.

Both the CDC and U.S. Food and Drug Administration advise against serology testing being used as a method of diagnosing an active COVID-19 infection, as antibodies can appear anywhere from one to three weeks after contracting the virus.

However, serology testing can be effective in detecting a previous COVID-19 infection in someone who may not have otherwise known due to a lack of displayed symptoms or asymptomatic infection.

To date, the FDA has issued four emergency use authorizations for serology testing and is actively considering applications from developers.

What is the science behind it?

According to Dr. Kaitlyn Sadtler, a bioengineering investigator for the National Institute of Biomedical Imaging and Bioengineering, if a person contracts the coronavirus, the bodys immune system is induced to develop specific antibodies in response to antigen proteins in the virus.

Our body will recognize those [proteins] and make antibodies to tag the virus for destruction, Sadtler said. What we can do is, in a [petri] dish, go ahead and put those proteins at the bottom of the dish and put our patients ... blood serum on that, and then see if we have antibodies that are binding to those protein.

If the samples antibodies bind with COVID-19 proteins, the test will be considered positive for previous infection. However, Sadtler said labs usually validate these tests by repeating the process with other, past coronavirus infections to ensure the antibodies were formed only in response to COVID-19.

It's important to note that some of these tests can be cross-reactive with previous coronaviruses so steps must be taken in validating the test to make sure that when you see something come up positive, it's actually a positive, and it's not saying, Oh, you had a seasonal coronavirus,' Sadtler said.

How can these tests help us to better understand COVID-19?

On April 10, the National Institutes of Health announced it was conducting a study with the National Institute of Biomedical Imaging and Bioengineering and others to gather information on undetected cases of COVID-19 infection.

The study seeks to collect blood samples via at-home collection kits from 10,000 healthy volunteers in the U.S. over the age of 18, which Sadtler said will help researchers gather information on cases of previous coronavirus infections that have gone undiagnosed.

First and foremost, we'll be able to understand the extent of the infection's spread in the United States, Sadtler said. Then, we can start partnering with other groups and start understanding the immunity to this virus.

While this study will contribute to further research, the presence of antibodies in the body does not guarantee immunity from the coronavirus, according to the CDC as of April 28.

Sadtler said even with the changing environment of the ongoing pandemic, the collection of serology tests will continue to be vital for health care providers to better understand COVID-19.

From the research [perspective], ... it'll be important to do both of these studies where we gather information at one point in time, as well as following people, for example, along multiple points in time, Sadtler said. It's important for us to utilize these validated and controlled assays at a number of times during and after the pandemic.

For more information about participating in the study, contact clinicalstudiesunit@nih.gov.

Excerpt from:
Serology testing explained: Here's what you need to know about COVID-19 antibody testing - Community Impact Newspaper