COVID antibodies are proteins created by your immune system that help you fight off a COVID-19 infection. Your body makes antibodies after you’ve been infected by the SARS-CoV-2 virus or have been vaccinated against an infection.

Antibodies may help protect you from the virus. The CDC reports that antibodies play an important role in helping prevent severe illness, hospitalizations, and death.

A COVID antibody test (sometimes referred to as a COVID serology test) looks for antibodies in your blood that fight the virus that causes COVID-19. In both children and adults, COVID antibody testing can help identify if you were exposed to SARS-CoV-2 coronavirus, and if exposed, check whether or not your body has produced a protective immune response.

• COVID antibody tests may be helpful if:

• You were never diagnosed with COVID-19 and are looking to determine if you may have been previously infected with the virus.
• You have previously tested positive for COVID-19 and want to know if your body has produced a protective immune response.
• You received a COVID-19 vaccine and want to know if your body has produced an immune response.
• You want to intermittently track if antibody levels remain detectable over time.

You were never diagnosed with COVID-19:

• Discover if you were previously infected with COVID.
• Confirm your body made a protective immune response to a prior COVID infection.
• Learn your personal current COVID antibody status and score – knowing your COVID antibody score gives you the option to track your COVID antibody levels for changes over time.

You previously tested positive for COVID-19:

• Confirm you made a protective immune response to a recent or past infection.
• Detect whether you still have protective COVID antibodies from your past infection.
• Learn your current COVID antibody level that you may choose to track over time for changes.

You tested positive for antibodies in the past from a prior COVID-19 infection:

• Check whether you still have detectable COVID antibodies from your prior infection.
• Learn your current COVID antibody level that you may choose to track over time for changes.

You previously received a COVID-19 vaccine:

• Confirm you made an immune response to a recent vaccine.
• Check whether you still have protective COVID antibodies from an old vaccine.
• Learn your current COVID antibody level that you may choose to track over time for changes.

You previously received a COVID-19 vaccine and also experienced a COVID-19 infection (in either order):

• Confirm you made antibodies from your recent vaccination or infection.
• Detect whether you still have protective COVID antibodies from your old immunizations and infections.
• Learn your current COVID antibody level that you may choose to track over time for changes.

You tested positive for antibodies in the past from a prior COVID-19 vaccine and/or infection:

• Check whether you still have detectable COVID antibodies from your prior vaccines or infections.
• Learn your current COVID antibody score that you may choose to track over time for changes.

Please Note: If you’re vaccinated and want to confirm you had a previous COVID infection, you’ll need to check out our Comprehensive COVID Antibody Test.

You have an immunodeficiency disorder that makes your body more susceptible to infections:

• Lets you determine whether you produced a protective immune response from your prior COVID vaccination and/or infection.
• Allows you to intermittently track your COVID Antibody Score for interval changes to verify your antibody levels remain detectable over time.

If you are non-vaccinated, a spike antibody test like this can tell if you’ve already had a COVID-19 infection. A positive spike antibody test result in a non-vaccinated individual is representative of a prior COVID-19 infection. When positive, this semi-quantitative test will also provide your antibody level, which helps you understand the relative strength of your results.

If you are vaccinated, this spike antibody test cannot tell if you’ve already had a past COVID-19 infection. COVID-19 vaccines authorized in the USA are designed to induce a spike antibody response. As such, a positive spike antibody test result will inform a vaccinated individual whether their body has made an antibody response to a COVID-19 vaccine and/or infection and provide their total COVID antibody level. This is useful to determine whether the body still has antibodies from an old COVID-19 vaccine and/or infection. You can also use this test to confirm if the immune system produced a robust antibody response to a new vaccine or infection.

Vaccinated individuals can only utilize a nucleocapsid covid antibody test to see if they had a prior COVID-19 infection. A nucleocapsid test measures antibodies to the nucleocapsid protein on the SARS-CoV-2 virus. This protein is only found on the virus and is not a component of the current COVID-19 vaccines. So, a positive nucleocapsid antibody result (regardless of your vaccine status) indicates the body has already had a COVID-19 infection and has antibodies against it. The nucleocapsid test is also helpful for non-vaccinated individuals. Non-vaccinated individuals can use it as an additional marker to the spike antibody test to confirm a prior COVID-19 infection. Using two antibody markers to detect a past COVID-19 exposure is especially beneficial in mild or asymptomatic illness and when trying to detect an old COVID-19 infection.

If you’re interested in testing for both spike and nucleocapsid antibodies, check out our Comprehensive COVID Antibody Test.

Everyone has a different baseline antibody level response to a COVID-19 vaccine or infection.

A protective immune response to a natural COVID-19 infection or vaccine may produce antibodies against COVID-19. It takes most people with a healthy immune system 1 to 3 weeks after exposure to a COVID-19 vaccine or infection to develop antibodies. Not everyone produces the same degree of antibodies to a COVID-19 infection or vaccination. Some individuals with mild or asymptomatic infections or those most at risk (i.e., the immunocompromised, people on immunosuppressant drugs, individuals with pre-existing conditions, etc.) may have diminished antibody response to a natural infection or vaccine.

After your body produces antibodies to a natural infection or vaccine, your antibody level typically wanes over time. Just as everyone has a unique baseline antibody response to a COVID-19 vaccine or infection, everyone experiences different rates of decline in antibody levels over time.

When antibodies drop too low, you may be more susceptible to infection. Scientists are still researching the threshold of protection for antibodies to SARS-CoV-2, the virus that causes COVID-19.

The CDC has not yet determined the antibody level that correlates with COVID-19 immunity. The CDC says if a SARS-CoV-2 infection happens, having antibodies plays an important role in helping prevent severe illness, hospitalizations, and death. It’s generally believed that the higher your antibody level, the greater your protection from an adverse outcome from a COVID-19 infection.

If it’s been 3 to 6 months or longer since your old COVID-19 vaccine or infection, for peace of mind you can use a semi-quantitative COVID antibody test like this to definitively check whether you still have antibodies.

Spike Covid Antibody Tests: Are often used by vaccinated individuals to measure their antibody level from an old or recent vaccine. The COVID-19 Antibody Test With Antibody Score is a spike antibody test that can detect antibodies from vaccines authorized in the USA and antibodies from a prior natural COVID-19 infection. A positive test gives you the total level of COVID antibodies in your body – regardless of whether they come from a previous vaccine and/or natural infection. Therefore this test cannot be used to confirm a prior COVID-19 infection in vaccinated individuals.

Nucleocapsid Antibody Test: Only a nucleocapsid antibody test can confirm a prior COVID-19 infection in a vaccinated individual. A nucleocapsid antibody test exclusively measures antibodies to the nucleocapsid protein on the SARS-CoV-2 virus and do not pick up antibodies from the vaccines currently authorized in the USA. To test for nucleocapsid antibodies, please see our Comprehensive COVID Antibody Test.

When testing for an antibody response to a recent COVID vaccine: It’s advised to wait at least three weeks after your immunization date to test.

When testing after a known COVID infection: Wait three weeks after your positive COVID test result date to test.

When testing after a suspected COVID infection: Wait 3 weeks after your symptoms started. If you didn’t have symptoms, test 3 weeks after your suspected exposure date or borderline/inconclusive rapid COVID test result.

This semiquantitative antibody test provides a positive or negative result along with your COVID Antibody Score, a numerical value of your antibody level. Knowing your level gives you an indication of the relative strength of your spike antibody results. Follow-up testing of your COVID Antibody Score can show changes to your immune response to previous COVID-19 infections and/or vaccines over time, so long as you use the same lab to evaluate for fluctuations in your antibody levels.

The upper detection limit of the spike antibody portion of this test is 1200 RU/ml. The higher your level, the stronger your antibody response.

Recently, specialists have published new scientific evidence in top peer-reviewed science journals. This new data shows that in patient samples analyzed with a semi-quantitative assay similar to that offered by 4U Health, higher levels of neutralizing antibodies correlate with increased protection from infection, reinfection, and severe disease. Additionally, specialists found that more seems better when it comes to protection against SARS-CoV-2 in this context.

Please note currently available SARS-CoV-2 antibody tests, including those offered by 4U Health, have not been authorized to determine what antibody level correlates with immunity. Knowing if you have antibodies to a prior COVID-19 infection or vaccine can provide valuable information about your immune system’s preparedness to fight off future infections. The CDC says if a SARS-CoV-2 infection happens, having antibodies plays an essential role in helping prevent severe illness, hospitalizations, and death.

You may test positive for antibodies even if you have never had symptoms of COVID-19 or have not yet received a COVID-19 vaccine. This indicates an infection without symptoms, which is called an asymptomatic infection.

A study published in JAMA Network Open found that, globally, more than 40% of confirmed COVID-19 cases were asymptomatic. Moreover, the Mayo Clinic reports up to 50% of children and adolescents might have COVID-19 with no symptoms.

COVID-19 vaccines teach your body to produce antibodies to the spike protein of SARS-CoV-2, to fight infection from the virus that causes COVID-19. If you get an antibody test after receiving a vaccine, you might test positive by some (but not all) antibody tests. This depends on which type of antibody the specific test detects.

This is a spike protein IgG COVID antibody test. The other methodology checks specifically for nucleocapsid IgG antibodies.

Spike Protein IgG Antibody Tests: A spike protein COVID-19 IgG antibody test detects an immune response to a previous COVID-19 infection or vaccine. It is useful for evaluating protective antibodies against the SARS-CoV-2 virus and whether acquired from a previous COVID-19 infection or vaccine immunization. This semi-quantitative spike protein IgG COVID-19 antibody test provides a Detected/Not Detected result and a COVID Antibody Score (level).

Nucleocapsid IgG Antibody Tests: A nucleocapsid protein COVID-19 IgG antibody test only detects an immune response to a previous COVID-19 infection. It is especially useful to help evaluate whether a vaccinated individual had prior exposure to SARS-CoV-2, but also used by non-vaccinated individuals. Keep in mind that (a) nucleocapsid proteins may not be as long-lasting, (b) IgG antibodies develop to spike but not to the nucleocapsid viral protein in many asymptomatic and light COVID-19 cases and (c) are not produced by vaccines authorized in the United States. If you’re vaccinated and want to confirm you had a previous COVID infection, you can check out our Comprehensive COVID Antibody Test that exclusively evaluates for antibodies from a prior COVID illness.

The spike protein is found on the surface of SARS-CoV-2, the virus causing COVID-19.

Spike Protein’s Role in Natural Infection
The key feature of the spike protein is to allow the virus to penetrate host cells within your body and cause infection. When SARS-CoV-2 enters the body, its spike protein acts as a key, gaining entry to the cell. The immune system responds by producing protective anti-spike antibodies that bind to the invading virus, blocking or neutralizing its effects.

Spike Protein’s Role in Vaccination
Without the S protein, viruses like the novel SARS-CoV-2 would not be able to interact with host cells to cause infection. As such, the spike protein makes an ideal target for vaccines. All currently available COVID-19 vaccines in the United States target the immune system to produce a protective anti-spike antibody response.

This is a spike protein IgG COVID antibody test and will detect a protective immune response to a previous COVID-19 infection or vaccine and provide your antibody level.

A positive spike COVID antibody test result shows your blood sample demonstrated antibodies made from an immune response to either a previous infection or vaccination for the virus that causes COVID-19, and at the time of the test, the antibodies were still present circulating in the blood.

Some antibodies made for the virus that causes COVID-19 provide protection from getting infected. CDC is evaluating what degree of safety COVID antibodies provide and how long protection from antibodies might last. Although infection is possible after having produced antibodies from vaccination or prior infection, having antibodies plays an important role in helping prevent severe COVID-19 disease.

Click Here to View a COVID-19 Antibody Test With Antibody Score Sample Report

To simplify and make COVID antibody testing less painful, 4U Health uses a finger stick dried blood spot sample method as part of its self-collection kit. To learn how easy it is to collect a dried blood spot specimen and mail it to the lab for testing, you can view this self-collection instructions video.

Test now or later. Your self-collection test kit will arrive with an expiration date of at least 5 months from your order date. That’s great news if you are buying multiple kits for yourself or want to gift to a friend or family member for later use. All test samples must be collected and mailed by the expiration date on your kit. Our current lot of test kits expire on December 31, 2023.

All 4U Health tests are eligible for gifting. In fact, they make great presents. The recipient who receives your gift will simply open the kit, register it, and follow the collection instructions. Within a few days of sending to the lab, your friend or family member will receive secure electronic HIPAA compliant results all thanks to your generosity.

Whether you have antibodies or not, you should get a viral test to evaluate for a current infection if you have COVID-19 like symptoms or have a suspected or confirmed exposure to someone with COVID-19. Click here for more information about an at-home saliva PCR COVID-19 test option.

Many people infected with COVID-19 are asymptomatic, meaning they do not experience symptoms. If you want to find out if you or your child had COVID-19, a 4U Health at-home COVID-19 antibody test is a simple way to learn your antibody status. Symptomatic patients with COVID-19 often report a wide range of symptoms anywhere from 2 to 14 days after exposure to the virus. If you have experienced one or more of the following symptoms, it increases the likelihood of having had a COVID-19 infection.

• Head

• Loss of taste or smell
• Sinus congestion or runny nose

• Body

• Diarrhea
• Fatigue or general body weakens
• Fever or chills
• Muscle or body aches
• Nausea or vomiting

• Respiratory

• Cough
• Shortness of breath or difficulty breathing
• Sore throat

A COVID antibody test may NOT be right for you if you are trying to diagnose COVID-19. COVID antibody tests are not approved to diagnose an active COVID-19 infection. A COVID antibody test only shows whether the body has developed an adaptive immune response to the virus as part of a prior infection or vaccine. To test for an active COVID-19 infection, click here.

• You should not get a COVID antibody test if:

• You feel sick or have had a fever within the last 3 days, please contact a healthcare provider.
• It is less than 10 days since you tested for and were diagnosed with COVID-19.
• You were directly exposed to COVID-19 in the past 14 days.
• It is less than 2 weeks since you had your complete vaccination for COVID-19.
• You live in New York State, Pennsylvania, or Maryland. This serology test is unavailable for self-collection in NY, PA or MD.

COVID antibody testing identifies individuals with an adaptive immune response to SARS-CoV-2, indicating recent or prior infection. The test provides semi-quantitative detection of IgG antibodies to SARS-CoV-2 in human finger stick by dried blood spot (DBS) specimens. Antibody tests are self-collected at home by individuals aged 18 years or older or collected by adults from individuals 5 years of age and older using the COVID-19 Self-Collected Antibody Test System. Home COVID antibody test kits are ordered when appropriate by a healthcare provider licensed to practice medicine in the state where a specimen is self-collected. 4U Health includes a telehealth medical practitioner order in the test cost.

At this time, it is unknown for how long antibodies persist following infection (or vaccination) and if the presence of antibodies confers protective immunity.

This at-home self-collection serology test system has not been FDA cleared or approved but has been authorized for emergency use by the FDA. This test system has been authorized only for detecting IgG antibodies to SARS-CoV-2, not for any other viruses or pathogens.

The emergency use of this at-home self-collection serology test system is only authorized for the duration of the declaration that circumstances exist justifying the authorization of emergency use of in vitro diagnostics for detection and/or diagnosis of COVID-19 under Section 564(b)(1) of the Federal Food, Drug and Cosmetic Act, 21 U.S.C. § 360bbb-3(b)(1), unless the declaration is terminated or authorization is revoked sooner.

4U Health tests meet national standards and are as accurate as services provided in a doctor’s office or hospital. We only work with the highest quality CLIA certified laboratories and health experts. All testing complies with state and federal regulations. And our clinicians provide medical oversight throughout the entire process.

Rest assured; HIPAA security standards protect your data every step of the way while determining your COVID antibody status. Keeping your confidential data secure is our number one priority. We only share your information when required to deliver our products and services or where we are legally obligated to do so. Your results are securely protected and available for review in your online portal; always secure but easily accessible only to you.

Pay upfront and receive no surprise medical bills. 4U Health is not enrolled in Medicare or any other private insurance network. This test is not eligible for Medicare or any other federal or state-funded insurance program reimbursement.

It usually takes between 1 to 3 weeks after infection or vaccination for the body to make COVID-19 antibodies. A false negative result may sometimes occur if you get an antibody test too soon after being exposed or vaccinated and your body has not yet made enough antibodies to be detected by the test. To help avoid a false negative result, collect your COVID antibody specimen no sooner than 21 days after a suspected exposure or immunization.

Additionally, some immunocompromised individuals, often those with weakened immune systems due to a medical condition or certain medications, may not develop detectable levels of antibodies after exposure or vaccination.

Although rare, a false positive test result may occur if the test cross-reacts and detects antibodies from other coronaviruses, like the virus that causes the common cold.

If you’re having trouble understanding your results, we advise you follow up with a healthcare provider who can evaluate your medical history.

A COVID antibody test can help identify individuals who have developed an immune response after exposure to COVID-19 or vaccination.

Although infection is possible after having produced antibodies from vaccination or prior infection, having antibodies is thought to play an important role in helping prevent severe COVID-19 disease. The CDC does not advise using this test to determine your immunity level of protection. Evidence is still being collected and studied to determine if antibodies, and at what level, provide protective immunity against SARS-CoV-2 (COVID-19) specifically.

Follow up with your healthcare provider for additional guidance on how to interpret your test results.

In reference to antibody numbers, please note there are no generally recognized international standardized units or antibody levels for COVID Antibody Tests allowed by the FDA at this time. As such, if you already had an antibody level from another test, it is generally advised you follow up with the same test by the same lab to evaluate for an interval change between two results. Again, we do not recommend comparing a numerical antibody level from one type of COVID Antibody test to another different kind of antibody level test for an interval change.

Follow up with your healthcare provider for additional guidance on interpreting your test results, particularly how they may compare to previous results obtained from another test assay.

How do I view this antibody serology test’s FDA (EUA) authorization?
FDA Emergency Use Authorization. Updated June 24 2021. Accessed December 9, 2022.

How do I view this antibody serology test’s FDA fact sheet for recipients?
FDA Fact Sheet for Recipients. Updated April 5, 2021. Accessed December 9, 2022.

How do I view this antibody serology test’s fact sheet for healthcare providers?
FDA Fact Sheet for Healthcare Providers. Updated June 24, 2021. December 9, 2022.

Where can I find additional information about COVID-19 antibodies testing?
For additional information about COVID-19 antibody testing, visit the FDA website or CDC website.

A.D.A.M. Medical Encyclopedia. COVID-19 antibody test. URL. Updated August 5, 2022. Accessed December 9, 2022.

A.D.A.M. Medical Encyclopedia. COVID-19 virus test. URL. Updated August 5, 2022. Accessed December 9, 2022.

Centers for Disease Control and Prevention. Using antibody tests for COVID-19. URL. Updated February 24, 2022. December 9, 2022.

Caliendo AM, Hanson KE. COVID-19: Diagnosis. In: Hirsch MS, ed. UpToDate. URL. Updated September 1, 2022. December 9, 2022.

Centers for Disease Control and Prevention. Test for past infection. URL. Updated September 28, 2022. December 9, 2022.

Centers for Disease Control and Prevention. COVID-19 testing overview. URL. Updated September 28, 2022. December 9, 2022.

Centers for Disease Control and Prevention. Interim guidelines for COVID-19 antibody testing. URL. Updated September 24, 2022. December 9, 2022.

Centers for Disease Control and Prevention. Self Testing. URL. Updated September 6, 2022. December 9, 2022.

Kim AY, Gandhi RT. COVID-19: Management in hospitalized adults. In: Hirsch MS, ed. UpToDate. URL. Updated September 9, 2022. December 9, 2022.

McIntosh K. COVID-19: Epidemiology, virology, and prevention. In: Hirsch MS, ed. UpToDate. URL. Updated November 10, 2022. December 9, 2022.

The New York Times. Wondering if the vaccine worked? Get the right test, at the right time. URL. Updated June 28, 2021. December 9, 2022.

UpToDate. COVID-19: Questions and answers. URL. Updated December 6, 2022. December 9, 2022.

UpToDate. Patient education: COVID-19 overview (the basics). URL. Updated February 28, 2022. December 9, 2022.

US Food and Drug Administration. Antibody (serology) testing for COVID-19: Information for patients and consumers. URL. Updated February 24, 2022. December 9, 2022.

US Food and Drug Administration. Coronavirus (COVID-19) update: FDA issues emergency use authorization for the symbiotica COVID-19 self-collected antibody test system. URL. Updated April 6, 2021. December 9, 2022.

US Food and Drug Administration. Coronavirus disease 2019 testing basics. URL. Updated February 28, 2022. December 9, 2022.

US Food and Drug Administration. In vitro diagnostics EUAs – serology and other adaptive immune response tests for SARS-CoV-2. URL. Updated December 6, 2022. December 9, 2022.

US Food and Drug Administration. SARS-CoV-2 viral mutations: Impact on COVID-19 tests. URL. Updated September 14, 2022. December 9, 2022.

World Health Organization. Coronavirus disease (COVID-19): Serology, antibodies and Immunity. URL. Updated December 31, 2020. December 9, 2022.

Yale Medicine. Which COVID-19 test should you use. URL. Updated January 20, 2022. December 9, 2022.

So you still have unanswered questions. No worries, we’d love to hear from you. Reach us by e-mail, phone or chat and we will do our best to provide answers so you can determine if this is the best test for you or your child.

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