Blood Test For COVID-19
The 2020 pandemic has led to many questions around COVID-19 and a lot of new vocabulary for many people. Questions often pop up, like: Can you test for COVID with a blood test? How long are COVID antibodies detectable? Does COVID show up in blood work? and it can be difficult to find the answers you need.
With so many new medical terms and processes, taking control of your health and understanding what options are available is important to help you make decisions that are right for you. There are so many COVID-19 testing options, and it can be confusing to know what each one is and why they are used.
We will look at what blood tests are for COVID-19 and answer frequently asked questions about this type of testing. Let’s dive in, and explore this subject together.
Are there any blood tests for COVID19?
Many people wonder, can a simple blood test detect COVID19? The answer is yes, but you can only find evidence of previous infections, not necessarily an active one. A blood test for Covid19 is known as an “antibody test” or a “serology test.” Your blood will be taken through a finger prick or by drawing from a vein in your arm. Next, they test that blood and look for the presence of antibodies to determine if you have had a COVID-19 infection in the past.
According to the CDC, you should not use an antibody test to diagnose a current infection of COVID-19, since it can take 1 to 3 weeks after infection for your body to produce antibodies.
Would COVID show up in routine blood work?
Most routine blood work panels do not include the COVID-19 antibody test at this time. Your doctor may order a serology test to check if you have had COVID-19 in the past, but the current standard blood work does not include looking for COVID-19 antibodies. Consult with your physician about what blood work you want done to find out if they are performing serology tests as part of the panel.
What is a COVID19 antibody test?
The COVID-19 antibody test works by using a process known as enzyme-linked immunosorbent assay (ELISA). Essentially, this process is applied to your blood sample in a lab and it looks for the presence of antibodies in your blood. Whenever a virus is introduced to your body, your immune system kicks in to produce antibodies to fight off that virus. These antibodies are proteins that your body makes, and they might be able to ward off future infections as well. The serology test is looking to see if your body has fought off Covid in the past by checking to see if you have those specific proteins in your blood, which can indicate a potential past infection.
Are COVID19 antibody blood tests considered accurate?
According to the CDC, the COVID-19 antibody tests are not 100% accurate and both false positive and false negative results may occur. The ELISA test has been issued an Emergency Use Authorization by the FDA during this global health crisis. Because this test is new, there is not as much data available to determine the accuracy rates of these tests, although scientists are working on figuring that out.
- A false positive can happen when you test positive for Covid antibodies but you don’t actually have any in your body. False positives may lead to you thinking that you have immunity when you actually do not, since you may not have had an infection in the past. Sometimes false positives occur because the test finds antibodies for other types of coronavirus, like the one that causes the common cold. Antibody tests also work better in populations with higher rates of SARS-CoV-2 infections, due to the PPV value (which we will look at momentarily).
- False negatives mean that the test did not detect any antibodies when you actually do have them. You may have been tested too soon after your infection and the test wasn’t able to detect the antibodies that are still developing in your body. It is also unclear if all individuals who have COVID-19 will have detectable antibodies, since some people might have had an infection but do not have enough antibodies in their blood to register on the test.
You may see PPV and NPV mentioned in your antibody results. This stands for Positive Predictive Values and Negative Predictive Values. Using the test’s sensitivity, specificity, and an assumption of the percentage of individuals in the population who have Covid antibodies, these measures help the health care professionals interpreting the test decide how likely it is that the result given is accurate or not.
Another common question is, can COVID19 antibody tests be used to evaluate immunity to COVID19? Due to the fact that researchers aren’t sure at this time if the presence of antibodies means you are immune, the FDA does not recommend using your COVID antibody test results range to determine whether or not you are immune to COVID-19.
You should talk to your doctor about your test results and they will be able to help you understand your results. They may want you to undergo a second serology test to confirm the results of the first test.
Am I immune to COVID19 if my antibody test result is positive?
Receiving a positive antibody test result does not necessarily mean you are immune to COVID-19. The CDC states that “currently, it is unknown if recovered adults are definitively immune to SARS-CoV-2 reinfection because biologic markers of immunity have not been correlated with protection from infection.” It is not known if you will be protected from being re-infected or if you are able to infect other people with SARS-CoV-2.
Positive Result With No Symptoms
If you fit these criteria, it is likely that you do not have a current infection and you can continue with normal activities, but should still follow the CDC recommendations for protecting yourself and others.
- Positive antibody result
- No symptoms of COVID-19
- Have not been around anyone who may have COVID-19.
Positive Result With Symptoms
If you fit these criteria, you should follow the CDC guidelines for quarantine.
- Positive antibody result
- You are currently or recently sick with Covid symptoms
- And/or you have been around someone who has COVID-19.
Be sure to consult your healthcare provider with any specific concerns or questions about your health.
How long does it take for COVID19 antibodies to fade?
There is not a lot of data currently answering the question, “how long do COVID antibodies last?” The CDC states that anyone who has tested positive for COVID-19 in the past 3 months and recovered does not need to quarantine or get tested if they are exposed again. A study from February of 2021 showed that there is evidence that peoples’ immune systems remember how to fight off COVID-19 for up to 8 months after an infection. This is still being studied and data is still being collected in order to understand how long antibodies last.
Can I go to work if I received a positive COVID19 antibody test result?
It depends on the requirements that your employer, state, and local government have in place for COVID-19 safety. Be sure to ask your employer what the criteria is for returning to work, and follow their workplace safety rules and regulations. It’s important to remember that a positive COVID-19 antibody test result does not necessarily mean you are immune to the virus.
Who should get an antibody test for COVID19?
Consult your healthcare provider to determine if a serology test would be appropriate for you. Since an antibody test cannot determine if you have a current infection, and should not be used to determine your immunity status, the information you may gather might not be particularly helpful for your unique situation. However, your doctor may want you to get an antibody test to shed some light on your medical history or may find it helpful to have that information on your medical record.
What tests are available to diagnose COVID-19?
Since antibody tests are not appropriate for diagnosing current infections, you will want to get either a PCR test or an antigen test (also known as the “rapid response” test). With these types of COVID-19 testing options, you can diagnose a current infection of SARS-CoV-2.
PCR Test
Known as the “gold standard” for COVID-19 testing, PCR tests work by taking a sample from your nose or throat and adding enzymes to convert the RNA to DNA. That DNA is then amplified and the amount of DNA present is measured to determine if you are positive or negative for COVID-19. These tests are considered the most accurate type of testing for current infections of SARS-CoV-2 that are available at the moment. PCR tests can take anywhere from 12 to 48 hours to receive a result, depending on the lab.
Antigen Test
The rapid response test is often used for the quick turnaround time, and can take as little as 15 minutes to get a result. It works by taking a sample and adding a substance that detects the presence of certain proteins that are part of the virus. The accuracy of antigen tests is not as high as PCR tests, and many doctors will order a PCR test to confirm the result of the rapid response test.
With any COVID-19 testing, it’s important to follow the CDC guidelines for what to do if you were exposed to someone who is positive for COVID-19. Protecting yourself and others from this deadly virus is the top priority, especially around high-risk individuals.
How can I get an COVID19 antibody test or a diagnostic test?
Antibody tests can be ordered by your healthcare provider. You may be able to find them at a local healthcare facility or testing center. You should talk to your doctor for more information and to determine if antibody testing is right for you.
BioCollections is here to help you with your COVID-19 testing needs
For COVID-19 testing, you can rely on the experts at BioCollections Worldwide. We have worked for over two decades perfecting rapid infectious disease testing as well as other essential tests utilized by doctors and private individuals. As the first lab testing for COVID-19 in the United States, and the first drive-through COVID-19 testing provider in Miami, Florida, we take our responsibility to give fast, accurate, and reliable results seriously.
Our on-demand COVID-19 PCR testing services are located in Florida, California, Nevada, and Puerto Rico. With a turn around time of 12 hours on PCR tests, you can rest easy knowing that you will receive accurate results in a timely manner with a trusted and reliable partner. Contact us today to learn more about our testing services and to determine if we can assist you on your healthcare journey.
