Covid-19 Antigen Testing: Analysis of Antigen Testing & The CDC

Learn about the different types of Covid-19 antigen rapid testing. Get information on CDC guidelines on licensing of laboratories, testing requirements, and collecting and handling the specimen. 

antigen rapid point of care test

Since the onset of Covid-19 in December 2019, antigen tests have been used widely to respond to the pandemic. There are CDC guidelines that laboratory professionals and clinicians who perform antigen tests, order antigen tests, receive the test results, and report on the test results. The analysis of antigen testing and the CDC guidance on the same will explore:

  1. The different types of SARS-COV-2 testing
  2. The Clinical Laboratory Improvement Amendments (CLIA) regulations on surveillance testing conducted by universities.
  3. The CLIA Enforcement on Centers for Medicare & Medicaid Services.
  4. The general guidance for rapid antigen testing for Covid-19.

The areas pointed out above will give you a clear picture of the CDC guidelines linked to antigen testing.

Covid-19 antigen testing 

There are several techniques and types of Covid-19 antigen testing, which are all designed to gather test results to be used to respond to the Covid-19 pandemic. Here are the three main tests used.

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  1. Surveillance testing

The goal of surveillance testing is to collect the data necessary to plan, evaluate, and implement public health practices. Covid-19 surveillance testing involves a continuous and systematic collection of test results. These results are then analyzed and interpreted to plan and evaluate responses or moves to make in combating and managing Covid-19.

The main objective of Covid-19 antigen surveillance testing is to investigate a community in light of the virus. With this testing, the relevant agencies are able to monitor the spread of the disease and identify its prevalence. As opposed to diagnostic testing, surveillance testing does not focus only on an individual level infection. Instead, it collects information on the prevalence and infections on a community level.

The results are also submitted collectively to the persons that request for them. Also, note that the results cannot be traced back to the individuals in surveillance testing, and the tested persons do not. Most countries are performing surveillance tests whereby samples in a population are selected for testing, after which the results are used to assess the rate of infestation and establish trends in the spread of the virus.

  1. Covid-19 diagnostic testing

The objective of diagnostic testing is to identify whether an individual has Covid-19. Diagnostic Covid-19 tests are done when a patient exhibits consistent symptoms with Covid-19 and when they are asymptomatic. Unlike antibody Covid-19 testing, diagnostic antigen testing is done to identify current infections.

  1. Screening testing

Screening testing is usually done in offices, schools, and many other congregational settings. Screening is done to people who have not reported any symptoms of Covid-19 and have no known exposure to the virus. The main objective of screening antigen testing is to identify persons who may have the virus to come up with strategies that will prevent its spread.

Screening for Covid-19 is done for statistical purposes, for the prevention of the spread of the virus, and for predicting the risk of infection of individuals in a population.

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In addition to diagnostic testing, surveillance testing, and screening testing, there is generalized surveillance testing which can be done by institutions like universities. Professionals and laboratories using antigen testing kits for generalized surveillance testing are not mandated to strictly abide by the set FDA and the Clinical Laboratory Improvement Amendments (CLIA) guidelines.

However, there is one guideline that the labs need to adhere to if they are using antigen testing for this purpose. That is, they should only use test kits that have been approved by the FDA. The professionals and labs conducting Covid-19 antigen testing can find information on the approved kits on the FDA website.

The Clinical Laboratory Improvement Amendments (CLIA) regulations on surveillance testing conducted by universities

Here are the set of CLIA guidelines on surveillance testing conducted by universities.

  • If you are an institution doing Covid-19 surveillance testing using pooled samples to make reports on Covid-19 results that are not patient-specific, you will not require a CLIA certification.
  • The information received or reported by this nature of surveillance testing must not be used to make any decisions. This is because the Centers for Medicare & Medicaid Services (CMS) do not consider surveillance testing as a tool for diagnosing Covid-19 infection.
  • Universities can conduct surveillance testing using antigen tests without necessarily being certified by CLIA.
  • Antigen testing techniques that are yet to be approved by the FDA can be used for surveillance testing under the provision that the patient-specific results should neither be reported nor used for decision-making purposes.
  • If the university intends to report the results, then they have to acquire a CLIA certificate.
 

Understanding CMS and CLIA enforcement

In light of reporting Covid-19 surveillance testing results, CMS is actively taking part in enforcing guidelines relevant to reporting patient-specific results of the tests. CMS cannot report surveillance testing results from laboratories and professionals that have not been certified by CLIA.

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infection. Antigen tests are conducted by placing a specimen into the test’s reagent. The specimen for antigen tests is authorized by CDC to be collected through nasal swabs or nasopharyngeal.

Laboratories and professionals need to keep the following guidelines in mind and adhere to them when conducting rapid antigen testing.

     1. Rapid antigen testing for different stages of infection

CDC recommends that rapid antigen tests for Covid-19 be done during the early stages of Covid-19 infection. This is mainly because it is during this time that the viral load is high and easy to detect. Following this recommendation will result in the effective and accurate performance of the tests.

Rapid antigen testing should also be done on individuals with exposure to the virus. The tests are also very instrumental for screening testing of populations with a high risk of exposure to the virus. The results of these tests can then be used to develop strategies for preventing the spread of the virus. Rapid antigen testing for Covid-19 has been recommended in situations where there is a need for prompt generation of results to control and prevent the spread of the virus in the population.

  1. Asymptomatic patients

CDC is yet to come up with a comprehensive guide on how rapid antigen tests should be conducted on asymptomatic patients. It is also not, however, clear on whether a previously infected person can still transfer the virus. With that, there has not been made any exceptions on asymptomatic patients in screening and Covid-19 antigen tests.

  1. The general guide for Covid-19 antigen testing

CDC has not set any age restrictions when it comes to antigen tests. This means that laboratories are allowed to collect specimens even from babies. The approved devices or kits for Covid-19 antigen testing are able to produce results within 15 minutes. Compared to the serology tests, antigen tests are less sensitive. These tests are also pretty affordable and can be done at the point-of-care.

Recommended CDC guidelines for the use and handling of Covid-19 antigen tests

  1. Surveillance testing

Note that laboratories and professionals are not mandated to comply with the CLIA and FDA requirements in line with surveillance testing for Covid-19 using the antigen tests. Nevertheless,

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Persons collecting specimens are also supposed to have personal protective equipment (PPE). The healthcare providers handling the specimen after collection may be different from the ones collecting. If that is the case, they are also required to comply with specimen handling procedures provided by the CDC.

Proper collection and handling of specimens go a long way in ensuring that the test results are accurate. It reduces the likelihood of getting false positives and negatives that might weigh down efforts strategized to combat the virus’s spread. The specimen should be collected, packages, shipped and transported in accordance with CDC guidelines. Persons handling patients and specimen should constantly wash their hands before, during and after handling specimen.

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The most that the universities can do in terms of reporting is to escalate inconclusive test results and presumed positives to CLIA certified labs for further testing.

Universities and CLIA licensing

In order to use the surveillance testing results, the university laboratories have to be certified by CLIA. Here is everything you need to know about CLIA certifying university laboratories.

  • Provided the primary site of a university laboratory has the CLIA certificate, the institution will not be forced to acquire more certificates for their laboratories that have been set up in temporary sites. Also, there is a provision that stipulates that the temporary labs have to work within the primary lab protocols if they are to work with the one CLIA certificate.
  • If the university laboratory is considered a temporary site for an existing CLIA certified lab, then getting another CLIA certificate will be unnecessary.
  • University laboratories that are not affiliated with existing CLIA-certified labs are also allowed to apply for the certificates. After a review of the CLIA certificate application guidelines after the emergence of the Covid-19 pandemic, this provision came about. The demand for more testing centers motivated the move.
  • To get the CLIA certificate, the applying lab must have a qualified lab director and provide the necessary information needed. The next step will be issuing a CLIA certificate number, after which the laboratory can begin testing.
  • University labs are allowed to use a qualified lab director from an existing lab. The lab can still be certified even if the director supervises the operations from a different lab location.
  • A university laboratory can be certified and be allowed to report on antigen surveillance testing if they contract a qualified director even if a university does not affiliate them.

These are the guidelines that university laboratories need to keep in mind if they are looking to acquire a CLIA certificate.

Detailed CDC guidelines for rapid antigen testing for Covid-19

Even before Covid-19, antigen tests were widely used to detect the presence of pathogens and, in particular, the ones present in the human respiratory system. Antigen tests are specific to a specific virus and are therefore used to detect the presence of a named virus to indicate a current

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laboratories are advised to use the recommended Covid-19 antigen test devices that have been approved by the FDA for better performance.

  1. Screening and diagnostic testing

Unlike in surveillance testing, laboratories and professionals are expected to adhere to the CDC and CLIA regulations in place while using Covid-19 antigen tests when diagnosing and screening infection.

  1. Rapid Covid-19 rapid test performance

The performance of antigen tests is considered to be inferior to antibody tests. As much as clinicians and laboratories are advised to use FDA-approved devices, there may still be a need to confirm the results produced by these tests. Note that antigen tests remain the tools to use for the detection of the virus. However, for accuracy purposes, the results must be further confirmed through a serology test.

CDC recommends that the confirmatory test be done within two days to maintain the accuracy of the specimen’s status.

  1. Handling of specimen

 The integrity of the test results relies heavily on the handling of the specimen. That is why the CDC came up with a set of guidelines to ensure the proper handling of the collected specimen. The specimen should also be collected within the shortest time possible after exposure to the virus or manifestation of Covid-19 symptoms.

The nasopharyngeal and oropharyngeal specimens will only be accepted if a health provider has collected them. Nasopharyngeal wash specimen collected by a healthcare provider is also accepted for Covid-19 antigen testing, and nasal swab specimen from on-site self-collection is also allowed.

CDC guidelines also stipulate that effective immediately after collection, the specimen or nasal swabs should be stored in a sterile transport tube. There is an exception where the specimen is going to be tested immediately. However, if it is to be transported to a laboratory, the mentioned handling guidelines must be followed.

Note that lower respiratory tract specimens such as sputum can also be collected for rapid Covid-19 antigen tests. To prevent healthcare providers’ infection, it is recommended that they collect the specimen while maintaining a distance of 6 feet.

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References

https://www.cdc.gov/coronavirus/2019-ncov/downloads/Viral-Transport-Medium.pdf

https://www.cdc.gov/coronavirus/2019-ncov/downloads/Viral-Transport-Medium.pdf

https://www.fda.gov/medical-devices/coronavirus-disease-2019-covid-19-emergency-use-authorizations-medical-devices/vitro-diagnostics-euas

https://www.cdc.gov/coronavirus/2019-ncov/downloads/Viral-Transport-Medium.pdf

https://www.cdc.gov/coronavirus/2019-ncov/lab/guidelines-clinical-specimens.html

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