RAPID FLU TESTING

Effective Date: 
Thu, 08/01/2013
Reviewed: 
Mon, 02/27/2017
Revised: 
Mon, 02/27/2017
Policy: 

Purpose and Scope:

Influenza is a highly contagious, acute, viral infection of the respiratory tract. The
causative agents of the disease are immunologically diverse, single-strand RNA viruses known as influenza viruses. There are three types of influenza viruses: A, B, and C.
Type A viruses are the most prevalent and are associated with most serious epidemics. Type B viruses produce a disease that is generally milder than that
caused by type A. Type C viruses have never been associated with a large epidemic of human disease. Both type A and B viruses can circulate simultaneously, but usually one type is dominant during a given season.

Influenza antigens may be detected in clinical specimens by immunoassay. The
QuickVue Influenza A+B Test is a lateral-flow immunoassay using highly sensitive
monoclonal antibodies that are specific for influenza antigens. The test is specific to
influenza types A and B antigens with no known cross-reactivity to normal flora or other known respiratory pathogens.

Reagents and Supplies:

Individually Packaged Test Strips (25): Mouse monoclonal anti-influenza A and anti-
influenza B antibodies

Reagent Solution (25): Vials with 340

μL of salt solution

Reagent Tubes (25): Lyophilized buffer with detergents and reducing agents

Disposable Droppers (25)

Sterile Nasal Swabs (25)

Positive Influenza Type A Control Swab (1): Swab is coated with non-infectious
recombinant influenza A antigen

Positive Influenza Type B Control Swab (1):Swab is coated with non-infectious
recombinant influenza B antigen

Negative Control Swab (1): Swab is coated with formalin-inactivated, non-infectious Streptococcus C antigen

Quality Control:

Built-in Control Features

The QuickVue Influenza Test contains built-in procedural control features. The
manufacturer's recommendation for daily control is to document these built-in
procedural controls for the first sample tested each day.

The two-color result format provides a simple interpretation for positive and negative results. The appearance of a blue procedural Control Line provides several forms of positive control by demonstrating sufficient capillary flow has occurred and the functional integrity of the Test Strip was maintained.
If the blue procedural Control Line does not develop at 10 minutes, the test result is considered invalid.

A built-in negative control is provided by the clearing of red background color, verifying that the test has been performed correctly. Within 10 minutes, the result area should be white to light pink and allow the clear interpretation of the test result.
If background color appears and interferes with interpretation of the test result, the result is considered invalid. Should this occur, review the procedure and repeat the test with a new Test Strip.

External Quality Control

External controls are also used to demonstrate that the reagents and assay
procedure perform properly.
Quidel recommends that positive and negative controls be run once for each untrained operator, once for each new shipment of kits- provided that each different lot received in the shipment is tested - and as deemed additionally necessary by your internal quality control procedures, and in accordance with local, state, and federal regulations or accreditation requirements.
If the controls do not perform as expected, repeat the test or contact Quidel Technical Support before testing patient specimens.
External positive and negative control swabs are suppliedin the kit and should be
tested using the Swab Procedure.

Procedure

SPECIMEN COLLECTION

Nasal Swab Sample:

For proper test performance, use the swabs supplied in the kit.

To collect a nasal swab sample, insert the sterile swab into the nostril that presents the most secretion under visual inspection. Using gentle rotation, push the swab until resistance is met at the level of the turbinates (less than one inch into the nostril).

Rotate the swab a few times against the nasal wall.

Nasal Wash or Aspirate Sample:

For Older Children and Adults:

With the patient's head hyper-extended, instill about 2.5 mL of sterile, normal saline into one nostril with a syringe.

To collect the wash, place a clean, dry specimen container directly under the nose with slight pressure on the upper lip.

Tilt the head forward and allow the fluid to run out of the nostril into the specimen container.

Repeat for the other nostril and collect the fluid into the same specimen container.

Nasal Swab Procedure

Dispense all of the Extraction Reagent Solution from the Reagent Tube. Gently swirl the Extraction Tube to dissolve its contents.

Place the patient swab sample into the Extraction Tube. Roll the swab at least three (3) times while pressing the head against the bottom and side of the Extraction Tube.

Roll the swab head against the inside of the Extraction Tube as you remove it. Dispose of the used swab in accordance with your biohazard waste disposal protocol.

Place the Test Strip into the Extraction Tube with the arrows on the Test Strip pointing down. Do not handle or move the Test Strip until the test is complete and ready for reading.

Read result at ten (10) minutes. Some positive results may appear sooner.

Nasal Wash/Nasal Aspirate Procedure

Fill the dropper to the top/uppermost notch with nasal wash or nasal aspirate sample.

Add entire contents of the dropper to the Extraction Tube. Swirl the Extraction Tube gently to dissolve its contents.

Place the Test Strip into the Extraction Tube with the arrows on the Test Strip pointing down.

Do not handle or move the Test Strip until the test is complete and ready for reading.

Read result at ten (10) minutes. Some positive results may appear sooner.

INTERPRETATION OF RESULTS

Positive Result*:

At ten minutes, the appearance of ANY shade of a pink-to-red Test Line either above or below the Blue Control Line AND the appearance of a blue procedural Control Line indicates a positive result for the
presence of influenza A and/or B viral antigen.

Hold the Test Strip with the arrows pointed down.

If the red line is above the Control Line, the test results are positive for type A.

If the red line is below the Control Line, the test results are positive for type B.

*A positive result does not rule out co-infections with other pathogens or identify any specific influenza A virus subtype.

Negative Result**:

At ten minutes, the appearance of ONLY the blue procedural Control Line indicates
influenza A and B viral antigen were not detected. A negative result should be reported as a presumptive negative for the presence of influenza antigen.

**A negative result does not exclude influenza viral infection. Negative results should be confirmed by cell culture.

Invalid Result:

If at ten minutes, the blue procedural Control Line does not appear, even if any shade of a pink-to-red Test Line appears, the result is considered invalid. If at ten minutes, the background color does not clear and it interferes with the reading of the test, the result is considered invalid. If the test is invalid, a new test should be performed with a new patient sample and a new Test Strip.

REFERENCES

Quidel QuickVue Influenza A+B Test Package Insert #1063811 Ver (06/14)

Murphy, B.R., and R.G. Webster. 1996.Orthomyxoviruses, pp. 1397–1445. In:
Fields Virology, 3rd edition, B.N. Fields,D.M. Knipe, P.M. Howley, Et al. (eds.),
Lippincott-Raven, Philadelphia.