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Introduction to the ZstatFlu™ Test


ZstatFlu™ Test Components: Descriptions, Ordering Information, and Storage


Specimen Collection and Handling


Test Reimbursement Issues


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Introduction to the ZstatFlu™ test

 What is the ZstatFlu™ test, and how does it work?

The ZstatFlu™ test, from ZymeTx, Inc., is the only diagnostic test that detects both influenza A and B with 99% specificity from a patient-friendly and doctor-preferred throat swab specimen. This test is an endogenous viral-encoded assay (EVEA) that reports the catalytic cleavage of the ZstatFlu™ substrate by influenza neuraminidase, an essential enzyme needed for both viral infectivity and propagation. The ZstatFlu™ substrate is a carefully designed molecule that only influenza neuraminidase can utilize. When influenza neuraminidase encounters the ZstatFlu™ substrate the molecule is split into two parts, releasing a blue-colored precipitate that is collected on the filter of the collection device included in the kit. The visible presence of this blue precipitate indicates a positive test result.


ZstatFlu bridges the gap between vaccination and treatment, completing a comprehensive Influenza Disease Management Program.

The package insert for the ZstatFlu™ rapid influenza diagnostic test is available online.

 Why should I use the ZstatFlu™ Test instead of another influenza diagnostic?

Unlike other tests, the ZstatFlu™ test does not use antibody-enzyme conjugates to detect influenza antigens. Instead, the test is a neuraminidase assay. This fact is important for several reasons. First, molecular comparisons have shown that the neuraminidase enzyme (and other influenza proteins detected by antibody-based tests) are prone to mutation and can vary considerably from one strain to another. However, the neuraminidase active site, the portion of the enzyme that binds to and splits the ZstatFlu™ substrate, is highly conserved in all strains of influenza A and B studied. This means you can feel confident that the ZstatFlu™ test will not "miss" new strains of the flu as they emerge. This is an assurance that no antibody-based test can offer. In fact, the ZstatFlu™ test has successfully detected every strain of type A or B influenza that has been tested, including many avian and swine strains from which future influenza strains may develop!

A second reason to choose the ZstatFlu™ test over the competition is that the ZstatFlu™ diagnostic detects influenza at the neuraminidase active site - the same site targeted by next-generation flu drugs. This class of therapeutics is known as neuraminidase inhibitors and includes Glaxo's Relenza® and Roche's Tamiflu®. As a result, the ZstatFlu™ test offers clinical diagnosis at the same molecular target used by the most effective flu drugs. Early stage ZstatFlu™ diagnosis and treatment with neuraminidase inhibitors go hand-in-hand.

Other reasons to choose ZstatFlu™ include:

  • 99% specificity means you can prescribe influenza therapeutics with confidence.
  • Sample collection uses a patient-friendly, doctor-preferred throat swab and is readily portable, with specimen stability for up to 24 hours at room temperature with no needed additives.
  • The test is rapid, requiring a 20 minute incubation step and less than 2 minutes of hands-on time. This means patients can be tested, diagnosed, and an antiviral therapeutic prescribed, all within 30 minutes! The fast, simple test format also means more tests/hour, fewer errors in testing, and a lower overall cost burden per test.
  • Competitive pricing. This price-point, coupled with resources available through ZymeTx's National Flu Surveillance Network, provides a cost-effective disease management strategy that has been proven to reduce patient expenses associated with influenza.

Still unconvinced? Compare the ZstatFlu™ test with other rapid influenza diagnostic tests:

IssueZstatFlu™ TestOther Antibody-based Tests
Detection TechnologyNeuraminidase assay technology reports enzyme activity at the same site of action targeted by new flu drugsAntigen-Antibody detection not matched with the therapeutic mechanism of new flu drugs
Test ComplexityTest is performed in four simple steps using only two solutions. Less than two minutes of hands-on time is required per test.Some tests require as many as 8 different steps and 8 separate solutions. As much as 15 minutes of hands-on time is needed per test.
Influenza Type DetectedBoth type A and B detected with roughly comparable sensitivity and specificitySome tests detect only influenza A
Clinical DataZstatFlu™ is the only rapid influenza diagnostic that reports clinical data for sensitivity and specificity for BOTH influenza A and BClinical data reported only for influenza A or combined type A and B. Sensitivity and specificity for influenza B is unknown.
Specimen CollectionPatient-friendly and doctor-preferred throat swabThroat swab is not always an option. Some tests require a patient-unfriendly nasal wash and/or unconventional nasal swab.
Specimen StabilitySpecimen stable for testing up to 24 hours after collectionTesting should be performed as soon as possible. Depending on the test, specimens must be stored under refrigerated conditions or cannot be stored at all.
Specimen TransportTransport possible at ambient temperature (32-104 F); materials for transport are available in the existing kit components.Transport materials not always provided. Temperature extremes during transport cannot be tolerated.
On-board ControlsBuilt-in control confirms the use of the proper solutionUse of the appropriate test solution is not always indicated by the on-board control
External ControlsOnly two external controls are needed. Separate controls for influenza type A and B are not necessary since the molecular site of detection is identical for type A and B.Some tests require three controls: A negative control and two positive controls, one each for influenza type A and B.


 How is the ZstatFlu™ test performed?

The ZstatFlu™ test performed in 4 easy steps

  1. SWAB the back of the patient's throat thoroughly.
  2. COMBINE the specimen with the test diluent and dry reagent.
  3. INCUBATE the test solution at 41 C for 20 minutes.
  4. READ the results on the ZstatFlu™ collection device: Any shade of blue indicates the presence of flu.

 How much time is required to perform the test?

The total testing time requires a 20 minute incubation step and less than 2 minutes of hands-on time. For facilities that need to handle a large volume of clinical samples, samples can be batched or staggered during the incubation period to allow a throughput of dozens of tests per hour.

 How specific is the ZstatFlu™ test in diagnosing influenza?

In clinical trials conducted at two different sites, the ZstatFlu™ test detected influenza from throat swab specimens with 99% specificity and 62% sensitivity. The positive predictive value was 98% and the negative predictive value was 75%. Test performance was roughly comparable for both influenza type A and B, although the sensitivity of the test for type B (57%) was slightly lower than the sensitivity for type A (65%).

 Does the ZstatFlu™ test differentiate between type A and B influenza?

No. However, since the new flu drugs Relenza® and Tamiflu® target both type A and B (unlike amantadine and rimantadine, which are only effective against type A) a positive ZstatFlu™ diagnosis is all that is needed to prescribe therapeutics with confidence.

 What substances are known to interfere with the ZstatFlu™ test?

The ZstatFlu™ test is a neuraminidase assay. As with any enzyme assay, harsh chemicals (acid, base, detergents) may impair enzyme activity and reduce test performance. We have also observed that high concentrations of proteins such as serum proteins can interfere with the ZstatFlu™ assay. The simplicity and portability of the ZstatFlu™ test was designed around a throat swab specimen that needs no additives beyond those included with the kit. Thus it is critical that no additional reagents or material, such as transport media, be added to the throat swab specimen prior to testing.

 Is any regulatory certification needed to perform a ZstatFlu™ test?

Now CLIA Waived!

On December 4, 2000, the ZstatFlu ® test was classified as a waived test by the FDA under the Clinical Laboratory Improvement Amendments of 1988 (CLIA). Waived status greatly expands the number of physicians and facilities that can utilize the test. Waived tests "employ methodologies that are so simple and accurate as to render the likelihood of erroneous results negligible of pose no reasonable risk of harm to the patient if the test is performed incorrectly." According to the FDA, the CLIA waiver "allows a lab to perform the test without having to meet national personnel, quality assurance and proficiency testing standards."

CLIA regulations require that all entities that perform waived laboratory tests must have a Cerificate of Waiver, or higher laboratory certification. For more information about Clia Categorization, certification and how to obtain a Certificate of Waiver, you may click on any of the links below:

• FDA CLIA Pages
http://www.fda.gov/cdrh/clia/
• CDC CLIA Pages
http://www.phppo.cdc.gov/dls/clia/default.asp
• HCFA CLIA Pages
http://www.hcfa.gov/medical/clia/cliahome.htm
• CLIA and the Physicians Office Lab: Intepretive Guidelines
http://www.vh.org/providers/CMS/CLIA/LabGuidelines?A10Test.html
• HCFA Forms
http://www.hcfa.gov/forms
• CLIA Application for Certification Form HCFA-116
http://www.hcfa.gov/medicaid/clia/cliaapp.htm
• State Survey Agencies (CLIA Contact LIst)
http://www.hcfa.gov/medicaid/clia/ssa-map.htm

 What does a positive and negative ZstatFlu™ test result look like?

This is a very important question that is addressed through both textual and graphic descriptions in the ZstatFlu™ Visual Database of Test Positives and Negatives


ZstatFlu™ Test Components: Descriptions, Ordering Information, and Storage

 What components are included with the ZstatFlu™ test kit?

The DIAGNOSTIC LABORATORY TEST kit includes a filter tip, a diluent tube, a stop reagent tube, a dry reagent vial, a plastic transfer pipet, and a collection device with patient ID card and pH test strip. A SPECIMEN COLLECTION kit, consisting of a foam throat swab, a capped prefilter tube, and a patient ID card, is also included. POSITIVE AND NEGATIVE CONTROLS and a HEATING BLOCK are included in the first Starter Dispenser unit. POSITIVE AND NEGATIVE CONTROLS are also included in the Reorder Dispenser. Additional controls can be ordered separately.

ZStatFlu Package Heating Block Collection Device Transfer Pipet Dry Reagent Vial Prefilter Tube Foam-Tipped Throat Swab Diluent Stop Solution

 What types of ZstatFlu™ test kits and components are available for order?

The ZstatFlu™ test is provided in diagnostic laboratory format, and includes the following kits and component combinations:

  1. Starter Dispenser (order #90-010P). Contains 1 individually packaged SPECIMEN COLLECTION kit, 10 DIAGNOSTIC LABORATORY TEST kits, a HEATING BLOCK (preset to the 41 C operating temperature), and a POSITIVE AND NEGATIVE CONTROL kit. The standard formulation for the positive and negative controls is a swab containing dried materials. These swabs are single use only. Controls are also available in liquid form containing enough active ingredient to perform several control tests.
  2. Reorder Kits (order #90-020P). The basic "unit of reorder" of the Diagnostic Laboratory format is a dispenser containing 2 individually packaged SPECIMEN COLLECTION kits, 20 individually packaged DIAGNOSTIC LABORATORY TEST kits, and a POSITIVE AND NEGATIVE CONTROL kit.
  3. Specimen Collection Dispenser (order #P80-555). Contains 50 scored foam swabs, 50 capped prefilter tubes, and 50 patient ID labels.
  4. Control Dispenser (order #P70-500). Contains 5 positive and 5 negative dry swab control kits, each of which includes a capped prefilter tube with inserted positive or negative control swab, a filter tip, a diluent tube, a dry reagent vial, a stop reagent tube, a transfer pipet, and a collection device with patient ID card and pH indicator strip. These materials can be stored at room temperature.
  5. Bottled Liquid Control Dispenser (order #10-205). Contains a 1 ml solution of UV-inactivated, NON-INFECTIOUS influenza A virus, ATCC#-VR 100, H2N2, in a diluent solution containing 0.1% methyl paraben as a preservative. The Negative Control squeeze tube is mock culture fluid in a diluent solution containing the same preservative. Liquid controls are shipped overnight on wet ice, and must be stored at 4-8 C.
 How do I order the ZstatFlu™ test?

ZstatFlu® test kits can be ordered from your local distributor or directly from ZymeTx via email (orders@zymetx.com), phone (1-888-817-1314) or fax (1-877-854-4187).

 What are the ZstatFlu™ positive and negative controls?

The standard formulation for the positive and negative controls is a swab containing either dried, NON-INFECTIOUS influenza A virus or dried mock culture fluid. These swabs are single use only. The dry swab controls can be stored at room temperature, and may be ordered separately as a Dry Swab Control Reorder Dispenser (order #P70-500).

Controls are also available as a bottled liquid containing enough active ingredient to perform several control tests. The liquid Positive Control squeeze tube is a 1 ml solution of UV-inactivated, non-infectious influenza A virus, ATCC#-VR 100, H2N2, in a diluent solution containing 0.1% methyl paraben as a preservative. The Negative Control squeeze tube contains mock culture fluid in a diluent solution with the same preservative. Liquid controls are shipped overnight on wet ice, and must be stored at 4-8 C.

 Can I use any heating block?

ZymeTx strongly encourages you to use the heating block provided with the Starter Dispenser kit. This heating block has been carefully manufactured to ensure that the optimal temperature for the ZstatFlu™ test is maintained (40.5 ± 1.0 C). In addition, the ZymeTx heating block is sized to correctly fit the dry reagent vials and uniformly control the temperature of the test solution.

 How should ZstatFlu™ test kits be stored?

All components can be stored at room temperature (18-22 C). The only exception to this storage policy is that the liquid positive and negative controls, if you have them, must be stored at 4-8 C.

Specimen Collection and Handling

 Can the throat swab specimens be frozen prior to testing?

No. Throat swab specimens can be stored and transported to the laboratory for testing up to 24 hours after collection. Specimens should be handled within a temperature range of 0 C (32 F) to 40 C (104 F).

 Can I use specimens other than throat swabs with the ZstatFlu™ test?

Although it may be possible to employ other specimen types at some future date, the currently marketed version of the ZstatFlu™ test is only cleared for use with throat swab specimens.

 I would like to implement ZstatFlu™ testing in my medical practice. However, my office does not have an affiliated moderately complex laboratory facility. How can I take advantage of the ZstatFlu™ test?

If your office laboratory is not licensed by CLIA for moderately complex testing a satellite laboratory can perform the test for you. The portability and 24-hour stability of the throat swab specimen permits overnight testing at any one of a number of laboratories.

Test Reimbursement Issues

 What is the CPT code for the test?

According to our customers, the CPT codes most commonly used for the ZstatFlu® test in the past have been 86710 and 87449. However, the recently initiated code 82657 can also be used, and this new code appears to offer the best match to the ZstatFlu® test format. CPT 82657 was created to describe a test using "enzyme activity in blood cells, cultured cells, or tissue, not elsewhere specified; nonradioactive substrate, each specimen." No other code describes the ZstatFlu® test better than CPT 82657. This code exactly describes the test methodology on the following five major points:

  • ZstatFlu® detects influenza A and B neuraminidase enzyme activity
  • ZstatFlu® detects neuraminidase activity primarily in the infected tissue
  • ZstatFlu® uses a nonradioactive substrate
  • Detection of neuraminidase enzyme activity is not elsewhere specified
  • One ZstatFlu® test is performed for each specimen
In contrast, code 86710 is listed for an "antibody, influenza virus" test (but ZstatFlu® is not an antibody test), and code 87449 is listed as an "infectious agent antigen, detection by enzyme immunoassay technique qualitative or semiquantitative; multiple step method, not otherwise specified" (yet ZstatFlu® is not an enzyme immunoassay). It is important to remember that the coding preferred by individual payers may vary. You should always check with your payer in advance, or follow the coding instructions received from your specific payer after claims submission.

 How much does the test cost?

The ZstatFlu® test is competitively priced, and can be purchased from your local distributor or from ZymeTx. Please call 1-888-817-1314 for details.

 What is the reimbursement rate from insurance companies?

It's impossible for us to list the reimbursement rates for every insurer. However, reimbursement reports that we have received are as high as $50 on a fee for service claim, with an average reimbursement of $34. The best strategy is for someone from your office staff to contact the insurer and ask what the reimbursement would be for the relevant CPT code.

 What is the reimbursement under Medicare?

The Medicare reimbursement for CPT code 82657 is $24.96 and for CPT 86710, $18.74. However, this amount does vary by region.

 Will managed care pay for this test?

Managed care contracts vary. If you are captitated with a managed care company, check your contract to see if the test is included in your capitation. For more information, see the Physician's Resources section of the ZymeTx web site, or contact your Managed Care Representative and ask for their reimbursement policy for the CPT code that crosslists with the ZstatFlu™ test.

 I have a question not covered by this FAQ. How can I get help?

For more technical questions regarding test performance and troubleshooting, please see the ZstatFlu™ Technical FAQ and the ZstatFlu™ Visual Database of Test Positives and Negatives. If these resources do not offer a satisfactory answer to your question, please contact us by email (support@zymetx.com), phone (1-888-817-1314), or fax (1-877-854-4187).
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and ViraSTAT® are trademarks of ZymeTx, Inc.