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Putting Truth to the Test: Three Myths About Antibody Testing for COVID-19


What we know about the novel coronavirus is changing rapidly. Here are the latest facts about antibody testing for it.

By Dr. Don Liss, Vice President & Chief Medical Officer

Antibody tests, sometimes called serology tests, might be used as part of a successful strategy for fighting the novel coronavirus – from how to stop its spread to actively defending against it. But as antibody testing for COVID-19 increases across the United States, so does misinformation about it. Here’s what you should know:

Myth #1: Antibody tests can diagnose COVID-19.

There are two main types of tests associated with COVID-19 – viral tests and antibody tests. Only the viral test can diagnose an active infection with the virus. It requires a sample from the nasal cavity using a long swab. The test looks for parts of the actual virus. If the virus is present, the person is currently infected.

A COVID-19 antibody test is different. It’s a blood test that looks for the body’s response to infection; it doesn’t identify the actual virus. Antibodies are proteins that fight infections and may help protect against reinfection. Antibody tests can only tell if you have had been infected previously. Many people who were infected with the virus causing COVID-19 were asymptomatic and never even knew they were infected or may have had a mild cold or flu-like illness and never got tested for the virus.

Data from COVID-19 antibody tests tell us more about how the virus is spreading in communities and how many people have already been infected. It provides a snapshot of the infection across different times, in different areas and within different populations. This data helps public health experts understand how the virus is behaving and what strategies might be useful to protect people from getting infected.

Myth #2: All antibody tests are equal.

To date, no COVID-19 antibody test has proven 100 percent accurate, meaning they can produce false-negative or false-positive results. A false-negative happens when a person has had the coronavirus but the antibodies for it don’t show up on the test, whereas in a false-positive result antibodies are detected even though the patient never actually had an infection with the virus causing COVID-19. While none of the current antibody tests being used today are infallible, some are more accurate than others.

Antibodies don’t develop in the blood until 1-3 weeks after infection, which means an antibody test could return a negative result even if a person had, or even currently has COVID-19.

As we learn more about the novel coronavirus and the efficacy of different antibody tests, the Food and Drug Administration (FDA) is making changes to the requirements for new tests. This new information and resulting updates to guidelines should help improve antibody tests by making their results more accurate.

However, with so many different groups pushing to get their test to market during a pandemic, very few COVID-19 antibody tests have actually been approved by the FDA. And some that were initially allowed on the market have since been recalled. As of this article, the FDA has officially authorized only 12, most of which have happened in the last week or so. According to the Centers for Disease Control (CDC), the FDA has more than 200 additional COVID-19 antibody tests under various levels of review.

To extend the country’s test evaluation capacity, other governing bodies including the CDC, Biomedical Advanced Research and Development Authority (BARDA) and the National Cancer Institute/National Institutes of Health (NCI/NIH), have also been collaborating with the FDA to evaluate tests for emergency use during the pandemic – and have recently started sharing their test performance data with the public.

Myth #3: If you’ve had COVID-19 you can’t get it again.

When it comes to immunity, the jury is still out. We simply don’t have enough information about COVID-19 at this point to say for sure. While the presence of antibodies probably suggests some level of immunity, as is the case with other diseases (such as chickenpox or specific strains of the flu), we still do not know for sure and we don’t know the level of COVID-19 antibodies that would be needed for complete immunity.

Even if antibody levels were high enough to provide full immunity from the virus that causes COVID-19, we don’t know how long those antibodies would protect against reinfection. It could be a matter of months or a lifetime. We just don’t know yet.

What we do know is that social distancing, wearing a face covering and washing your hands frequently are still considered essential to fighting the spread of COVID-19. The CDC and the World Health Organization (WHO) strongly agree everyone should continue (or begin) to stay at least six feet away from others they don’t live with and wear a mask whenever they leave home.

Social distancing and wearing a face covering (over your mouth and nose) are still considered essential to fighting the spread of the coronavirus – regardless of whether or not you have tested positive for antibodies.

For more information from Horizon Blue Cross Blue Shield of New Jersey (Horizon BCBBSNJ) about COVID-19 and your Horizon BCBSNJ plan’s coverage related to it, visit horizonblue.com/coronavirus-2019.