COVID-19 ANTIBODY TESTING

The State of Arizona and The University of Arizona

University of Arizona Research Study – State of Arizona COVID-19 Antibody Testing Initiative FAQs

As part of a statewide research study, the University of Arizona is analyzing the blood samples of hundreds of thousands of Arizonans to determine who has developed antibodies against the virus that causes COVID-19. The State of Arizona is providing $3.5 million for the testing, which is available at more than two dozen locations across the state. The specific testing site for each participant will be selected during the registration process.

The following frequently asked questions provide additional information about the antibody testing program.

The tests, which are funded by the State of Arizona, are available for anyone in Arizona age 18 and older. Participants will need to show proof of age and photo ID upon check-in at the testing site.

An antibody is a protein made by immune cells that attaches to viruses, bacteria and fungi. There are four broad types of antibodies: IgM, IgG, IgA and IgE. The University of Arizona test measures total antibodies and does not distinguish between these four antibody types.

These types of blood tests detect whether your immune system has made proteins called antibodies. This test is for antibodies that attach to the coronavirus that causes COVID-19.

There are three types of tests that are being deployed during the pandemic – two that diagnose whether an individual is currently infected with the COVID-19 virus, and one that determines whether an individual has developed an immune response against the COVID-19 virus.

One type of diagnostic test is a polymerase chain reaction (PCR) test, a molecular diagnostic testing technique that detects the genetic material from the virus. PCR tests involve nasal swabs and can be incredibly accurate, but running the tests and analyzing the results can take time.

The other type of diagnostic test is an antigen test, which is a diagnostic test designed for rapid detection of the virus that causes COVID-19. An antigen test can provide results in minutes. Antigen tests, which also require a swab, are very specific for the virus but are not as sensitive as PCR tests. Positive results from antigen tests are highly accurate, but there is a higher chance of false negatives, so negative results may need to be confirmed with a PCR test.

The type of test that determines whether an individual has developed an immune response against the COVID-19 virus is a serological test that looks for antibodies to the virus, as part of either an active infection or a prior infection. These tests, which involve a blood draw, are not used to diagnose an active infection.

The antibody test developed by researchers at the University of Arizona Health Sciences is one of the most accurate in the country. The testing lab uses two different viral proteins, both of which must return antibody signals for a sample to be called positive. Tests have been further validated in the lab to confirm the presence of virus-neutralizing antibodies, the best available measure of immunological protection.

Most people who are infected by the virus make antibodies within a few weeks of infection. However, the amounts of antibodies vary among individuals. Low levels of antibodies might not be detected by this test.

The antibody tests will help us determine who has developed an immune response against the COVID-19 virus.

In the absence of symptoms, it is unlikely for someone to have a positive antibody test and currently be infected.

A positive test result indicates the presence of antibodies. By itself, it does not indicate current infection.

The presence of COVID-19 antibodies means your immune system mounted a response against the virus. We do not yet know the amounts of antibodies that are required to fully prevent subsequent infections, but there might be some level of protection. Because we still do not know enough about this virus, protection should not be assumed.

No. Both tests can detect antibodies and past infection, but there are differences. Finger-prick tests provide rapid YES/NO answers at a clinic or your doctor’s office. However, the accuracy of these tests is highly variable between manufacturers. The University of Arizona test requires a blood draw, and internal validation studies suggest that this test is likely more accurate than most finger prick tests.

The test is an enzyme-linked immunosorbent assay (ELISA). These ELISAs measure antibodies that bind to a part of the coronavirus spike protein called the receptor binding domain. In symptomatic patients tested 14 days or greater from diagnosis, the sensitivity of the test is 97.50% and the specificity is 99.06%.

This test is authorized by the FDA for use by University of Arizona Genetics Core for Clinical Services, pursuant to an Emergency Use Authorization (EUA). This test is only authorized for the duration of the declaration that circumstances exist justifying the authorization of emergency use of in vitro diagnostic tests for detection and/or diagnosis of COVID-19. Prior to receiving the EUA from the FDA, testing was allowed to begin while the FDA review process was underway.

Yes, this test will be conducted on the serum, which needs to be separated from the whole blood specimen within 2 hours of collection. Other specification requirements include:

  • Container: Red-top (no anticoagulant) or gold-top (serum separator tube; SST) collection tubes.
  • Minimum specimen requirement: 1.0 mL of serum from adult patients and 0.5 mL of serum from pediatric patients.
  • Transport to laboratory: Serum specimens should be delivered to the UAGC-CS location as soon as possible. If transport is delayed, serums specimens should be refrigerated (2-8 C).
  • Unacceptable specimens: Specimens which are severely lipemic and hemolyzed are not acceptable.

Serum separated from whole blood, either by gel/SST or manual transfer, is stable for:

  • up to 3 days at room temperature
  • up to 1 week when refrigerated at 2 8°C
  • up to 6 months when frozen (-20 C or lower)

Diagnosis of COVID-19 is made by detection of SARS-CoV-2 RNA by molecular testing methods, consistent with a patient’s history, clinical observations and epidemiological information.

Qualitative results for the antibody assay are reported as positive, negative or indeterminate.

A positive result may suggest an immune response to a primary infection of SARS-CoV-2, but the relationship between antibody positivity and immunity to SARS-CoV-2 has not yet been firmly established.

Negative or indeterminate results do not rule out SARS-CoV-2 exposure; it usually takes at least 10 days after symptom onset for antibody response to reach detectable levels.

The antibody test results and guidance for interpretation will be directly reported to individuals undergoing the test. Following analysis of all the results, de-identified aggregate data will be made available to the public.

Click on the “Sign-Up Required Here” link. You then will be asked to provide basic information about yourself, complete an online consent process and schedule an appointment using the online tool. You will receive an email confirmation with details about your appointment, including the date, time and directions to the facility.

For the safety of our team members, other participants and our community, individuals with COVID-19 symptoms will not be included in the initial phase of testing. All participants will be screened for symptoms before their appointment, and anyone showing symptoms will not move forward in the process.

In addition to testing sites in Pima County, where the first phase of the initiative began on April 30, new sites will begin opening the week of May 18 in the other 14 counties in Arizona. Overall, there will be 31 antibody testing sites across the state, with additional sites becoming available as needed. The specific testing site for each participant will be selected during the registration process.

Results from tests should be available 7-10 working days after the test. You will receive an email to let you know when your results are available.

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