The Sofia Influenza A+B FIA employs immunofluorescence to detect influenza A and influenza B viral nucleoprotein antigens in nasal swab, nasopharyngeal swab, and nasopharyngeal aspirate/wash in fresh or transport media specimens from symptomatic patients. This qualitative test is intended for use as an aid in the rapid differential diagnosis of acute influenza A and influenza B viral infections. The test is not intended to detect influenza C antigens. A negative test is presumptive and it is recommended these results be confirmed by virus culture or an FDA-cleared influenza A and B molecular assay. Negative results do not preclude influenza virus infections and should not be used as the sole basis for treatment or other management decisions. The test is intended for professional and laboratory use.
Device Story
Sofia Influenza A+B FIA is a lateral-flow immunofluorescence assay for detection of influenza A and B viral nucleoproteins. Input: nasal/nasopharyngeal swabs or aspirates/washes (fresh or in transport media). Process: specimen placed in reagent tube to disrupt virus particles; dispensed into cassette; lateral flow migration through test strip; Sofia analyzer scans strip to measure fluorescent signal. Output: qualitative result (Positive/Negative/Invalid) displayed on screen; optional printout. Used in professional/laboratory settings. Operation: Walk Away Mode (automated development in analyzer) or Read Now Mode (manual development then scan). Benefits: rapid differential diagnosis; aids clinical management decisions.
Clinical Evidence
Prospective clinical study (2011) of 1,991 valid specimens (nasal swab, nasopharyngeal swab, nasopharyngeal aspirate/wash) in VTM. Comparator: viral culture. Influenza A sensitivity: 83% (NS), 91% (NPS), 97% (NPA/W); specificity: 93-98%. Influenza B sensitivity: 80% (NS), 82% (NPS), 84% (NPA/W); specificity: 97-99%. Study population included 71% aged ≤5 years.
Technological Characteristics
Lateral-flow immunofluorescence immunoassay. Uses monoclonal antibodies specific for influenza A and B nucleoprotein antigens. Requires Sofia Analyzer for signal measurement and result processing. Standalone system for professional/laboratory use.
Indications for Use
Indicated for symptomatic patients requiring rapid differential diagnosis of acute influenza A and B viral infections. Specimens include nasal swabs, nasopharyngeal swabs, and nasopharyngeal aspirate/wash (fresh or in transport media). Not for influenza C detection.
Regulatory Classification
Identification
An influenza virus antigen detection test system is a device intended for the qualitative detection of influenza viral antigens directly from clinical specimens in patients with signs and symptoms of respiratory infection. The test aids in the diagnosis of influenza infection and provides epidemiological information on influenza. Due to the propensity of the virus to mutate, new strains emerge over time which may potentially affect the performance of these devices. Because influenza is highly contagious and may lead to an acute respiratory tract infection causing severe illness and even death, the accuracy of these devices has serious public health implications.
Special Controls
*Classification.* Class II (special controls). The special controls for this device are:(1) The device's sensitivity and specificity performance characteristics or positive percent agreement and negative percent agreement, for each specimen type claimed in the intended use of the device, must meet one of the following two minimum clinical performance criteria:
(i) For devices evaluated as compared to an FDA-cleared nucleic acid based-test or other currently appropriate and FDA accepted comparator method other than correctly performed viral culture method:
(A) The positive percent agreement estimate for the device when testing for influenza A and influenza B must be at the point estimate of at least 80 percent with a lower bound of the 95 percent confidence interval that is greater than or equal to 70 percent.
(B) The negative percent agreement estimate for the device when testing for influenza A and influenza B must be at the point estimate of at least 95 percent with a lower bound of the 95 percent confidence interval that is greater than or equal to 90 percent.
(ii) For devices evaluated as compared to correctly performed viral culture method as the comparator method:
(A) The sensitivity estimate for the device when testing for influenza A must be at the point estimate of at least 90 percent with a lower bound of the 95 percent confidence interval that is greater than or equal to 80 percent. The sensitivity estimate for the device when testing for influenza B must be at the point estimate of at least 80 percent with a lower bound of the 95 percent confidence interval that is greater than or equal to 70 percent.
(B) The specificity estimate for the device when testing for influenza A and influenza B must be at the point estimate of at least 95 percent with a lower bound of the 95 percent confidence interval that is greater than or equal to 90 percent.
(2) When performing testing to demonstrate the device meets the requirements in paragraph (b)(1) of this section, a currently appropriate and FDA accepted comparator method must be used to establish assay performance in clinical studies.
(3) Annual analytical reactivity testing of the device must be performed with contemporary influenza strains. This annual analytical reactivity testing must meet the following criteria:
(i) The appropriate strains to be tested will be identified by FDA in consultation with the Centers for Disease Control and Prevention (CDC) and sourced from CDC or an FDA-designated source. If the annual strains are not available from CDC, FDA will identify an alternative source for obtaining the requisite strains.
(ii) The testing must be conducted according to a standardized protocol considered and determined by FDA to be acceptable and appropriate.
(iii) By July 31 of each calendar year, the results of the last 3 years of annual analytical reactivity testing must be included as part of the device's labeling. If a device has not been on the market long enough for 3 years of annual analytical reactivity testing to have been conducted since the device received marketing authorization from FDA, then the results of every annual analytical reactivity testing since the device received marketing authorization from FDA must be included. The results must be presented as part of the device's labeling in a tabular format, which includes the detailed information for each virus tested as described in the certificate of authentication, either by:
(A) Placing the results directly in the device's § 809.10(b) of this chapter compliant labeling that physically accompanies the device in a separate section of the labeling where the analytical reactivity testing data can be found; or
(B) In the device's label or in other labeling that physically accompanies the device, prominently providing a hyperlink to the manufacturer's public Web site where the analytical reactivity testing data can be found. The manufacturer's home page, as well as the primary part of the manufacturer's Web site that discusses the device, must provide a prominently placed hyperlink to the Web page containing this information and must allow unrestricted viewing access.
(4) If one of the actions listed at section 564(b)(1)(A)-(D) of the Federal Food, Drug, and Cosmetic Act occurs with respect to an influenza viral strain, or if the Secretary of Health and Human Services (HHS) determines, under section 319(a) of the Public Health Service Act, that a disease or disorder presents a public health emergency, or that a public health emergency otherwise exists, with respect to an influenza viral strain:
(i) Within 30 days from the date that FDA notifies manufacturers that characterized viral samples are available for test evaluation, the manufacturer must have testing performed on the device with those viral samples in accordance with a standardized protocol considered and determined by FDA to be acceptable and appropriate. The procedure and location of testing may depend on the nature of the emerging virus.
(ii) Within 60 days from the date that FDA notifies manufacturers that characterized viral samples are available for test evaluation and continuing until 3 years from that date, the results of the influenza emergency analytical reactivity testing, including the detailed information for the virus tested as described in the certificate of authentication, must be included as part of the device's labeling in a tabular format, either by:
(A) Placing the results directly in the device's § 809.10(b) of this chapter compliant labeling that physically accompanies the device in a separate section of the labeling where analytical reactivity testing data can be found, but separate from the annual analytical reactivity testing results; or
(B) In a section of the device's label or in other labeling that physically accompanies the device, prominently providing a hyperlink to the manufacturer's public Web site where the analytical reactivity testing data can be found. The manufacturer's home page, as well as the primary part of the manufacturer's Web site that discusses the device, must provide a prominently placed hyperlink to the Web page containing this information and must allow unrestricted viewing access.
K131606 — SOFIA INFLUENZA A+B FIA · Quidel Corp. · Jul 5, 2013
K112177 — SOFIA ANALYZER AND INFLUENZA A+B FIA · Quidel Corp. · Oct 24, 2011
K162438 — Sofia Influenza A+B FIA on Sofia 2 · Quidel Corporation · Apr 14, 2017
Submission Summary (Full Text)
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# 510(k) SUBSTANTIAL EQUIVALENCE DETERMINATION DECISION SUMMARY
A. 510(k) Number:
K153012
B. Purpose for Submission:
This is a new 510(k) application to expand the nasal swab, nasopharyngeal swab, and nasopharyngeal wash/aspirate specimen types to include specimens in viral transport medium (VTM) for the Quidel Sofia Influenza A+B FIA. Under recommendations from FDA, Quidel has submitted limit of detection data and clinical study performance data to support the application.
C. Measurand:
Influenza A and B virus nucleoprotein antigens
D. Type of Test:
Qualitative immunofluorescence assay
E. Applicant:
Quidel Corporation
F. Proprietary and Established Names:
Sofia® Influenza A+B FIA
Influenza A+B immunological test system
G. Regulatory Information:
1. Regulation section:
21 CFR 866.3330, Influenza virus serological reagents
2. Classification:
Class I
3. Product code:
{1}
GNX – Influenza virus serological reagents
KHO – Fluorometer for clinical use
4. Panel:
Microbiology (83)
H. Intended Use:
1. Intended use(s):
The Sofia Influenza A+B FIA employs immunofluorescence to detect influenza A and influenza B viral nucleoprotein antigens in nasal swab, nasopharyngeal swab, and nasopharyngeal aspirate/wash in fresh or transport media specimens from symptomatic patients. This qualitative test is intended for use as an aid in the rapid differential diagnosis of acute influenza A and influenza B viral infections. The test is not intended to detect influenza C antigens. A negative test is presumptive and it is recommended these results be confirmed by virus culture or an FDA-cleared influenza A and B molecular assay. Negative results do not preclude influenza virus infections and should not be used as the sole basis for treatment or other management decisions. The test is intended for professional and laboratory use.
Performance characteristics for influenza A and B were established during February through March 2011 when influenza viruses A/California/7/2009 (2009 H1N1), A/Perth/16/2009 (H3N2), and B/Brisbane/60/2008 (Victoria-Like) were the predominant influenza viruses in circulation according to the Morbidity and Mortality Weekly Report from the CDC entitled "Update: Influenza Activity-United States, 2010-2011 Season, and Composition of the 2011-2012 Influenza Vaccine". Performance characteristics may vary against other emerging influenza viruses.
If infection with a novel influenza virus is suspected based on current clinical and epidemiological screening criteria recommended by public health authorities, specimens should be collected with appropriate infection control precautions for novel virulent influenza viruses and sent to state or local health department for testing. Virus culture should not be attempted in these cases unless a BSL 3+ facility is available to receive and culture specimens.
2. Indication(s) for use:
Same as intended use
3. Special conditions for use statement(s):
Prescription use only
4. Special instrument requirements:
2
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To be used only with the Sofia Analyzer
I. Device Description:
The Sofia Influenza A+B FIA employs immunofluorescence technology that is used with the Sofia Analyzer to detect influenza virus nucleoproteins.
The Sofia Influenza A+B FIA is a lateral-flow immunoassay that uses monoclonal antibodies that are specific for influenza antigens and have no known cross-reactivity to normal flora or other known respiratory pathogens.
Nasal swab, nasopharyngeal swab, and nasopharyngeal aspirate/wash specimens are used for this test. The patient specimen is placed in the Reagent Tube, during which time the virus particles in the specimen are disrupted, exposing internal viral nucleoproteins. After disruption, the specimen is dispensed into the cassette sample well. From the sample well, the specimen migrates through a test strip containing various unique chemical environments. If influenza viral antigen is present, they will be trapped in a specific location. The Sofia Analyzer will scan the test strip and measure the fluorescent signal by processing the results using method-specific algorithms. The Sofia Analyzer will display the test results (Positive, Negative, or Invalid) on the screen.
Quality Control
See decision summary for K112177.
Results Interpretation
See decision summary for K112177.
J. Substantial Equivalence Information:
1. Predicate device name(s):
Quidel Sofia Influenza A+B FIA
2. Predicate 510(k) number(s):
K112177
K131606
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# 3. Comparison with predicate:
Table 1 - Assay Comparison with Predicate Device
| | Predicate Device | Proposed Device |
| --- | --- | --- |
| Item | Sofia Influenza A+B FIA | Sofia Influenza A+B FIA |
| 510(k)Number | K112177 | K153012 |
| Regulation | 866.3330 | Same |
| Product Code | GNX, KHO | Same |
| Device Class | I | Same |
| Instrument | Sofia Analyzer | Same |
| Intended Use | The Sofia Influenza A+B FIA employs immunofluorescence to detect influenza A and influenza B viral nucleoprotein antigens in nasal swab, nasopharyngeal swab, and nasopharyngeal aspirate/wash specimens taken directly from symptomatic patients. This qualitative test is intended for use as an aid in the rapid differential diagnosis of acute influenza A and influenza B viral infections. The test is not intended to detect influenza C antigens. A negative test is presumptive and it is recommended these results be confirmed by virus culture or an FDA-cleared influenza A and B molecular assay. Negative results do not preclude influenza virus infections and should not be used as the sole basis for treatment or other management decisions. The test is intended for professional and laboratory use.Performance characteristics for influenza A and B were established during February through March 2011 when influenza viruses A/California/7/2009 (2009 H1N1), A/Perth/16/2009 (H3N2), and B/Brisbane/60/2008 (Victoria-Like) were the predominant influenza viruses in circulation according to the Morbidity and Mortality Weekly Report from the CDC entitled "Update: Influenza Activity-United States, 2010-2011 Season, and Composition of the 2011-2012 | The Sofia Influenza A+B FIA employs immunofluorescence to detect influenza A and influenza B viral nucleoprotein antigens in nasal swab, nasopharyngeal swab, and nasopharyngeal aspirate/wash in fresh or transport media specimens from symptomatic patients. This qualitative test is intended for use as an aid in the rapid differential diagnosis of acute influenza A and influenza B viral infections. The test is not intended to detect influenza C antigens. A negative test is presumptive and it is recommended these results be confirmed by virus culture or an FDA-cleared influenza A and B molecular assay. Negative results do not preclude influenza virus infections and should not be used as the sole basis for treatment or other management decisions. The test is intended for professional and laboratory use. Performance characteristics for influenza A and B were established during February through March 2011 when influenza viruses A/California/7/2009 (2009 H1N1), A/Perth/16/2009 (H3N2), and B/Brisbane/60/2008 (Victoria-Like) were the predominant influenza viruses in circulation according to the Morbidity and Mortality Weekly Report from the CDC entitled "Update: Influenza Activity--United States, 2010-2011 Season, and Composition of the 2011-2012 Influenza Vaccine". Performance |
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5
| | Influenza Vaccine". Performance characteristics may vary against other emerging influenza viruses. If infection with a novel influenza virus is suspected based on current clinical and epidemiological screening criteria recommended by public health authorities, specimens should be collected with appropriate infection control precautions for novel virulent influenza viruses and sent to state or local health department for testing. Virus culture should not be attempted in these cases unless a BSL 3+ facility is available to receive and culture specimens. | characteristics may vary against other emerging influenza viruses. If infection with a novel influenza virus is suspected based on current clinical and epidemiological screening criteria recommended by public health authorities, specimens should be collected with appropriate infection control precautions for novel virulent influenza viruses and sent to state or local health department for testing. Virus culture should not be attempted in these cases unless a BSL 3+ facility is available to receive and culture specimens. |
| --- | --- | --- |
| Assay Targets | Influenza A and Influenza B nucleoprotein antigens | Same |
| Specimen Types | Direct Nasal swab, Nasopharyngeal swab, and nasopharyngeal aspirate/wash specimens | Nasal swab, Nasopharyngeal swab, and nasopharyngeal aspirate/wash specimens both direct and in VTM |
| Test Time | 15 Minutes | 15 Minutes |
K. Standard/Guidance Document Referenced (if applicable):
N/A
L. Test Principle:
See decision summary for K112177.
M. Performance Characteristics (if/when applicable):
1. Analytical performance:
a. Precision/Reproducibility:
See decision summary for K112177.
b. Linearity/assay reportable range:
N/A
c. Traceability, Stability, Expected values (controls, calibrators, or methods):
N/A
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d. Detection limit:
# Limit of Detection (LoD)
LoD was established using two influenza A strains and two influenza B strains diluted into a negative pooled clinical matrix. The clinical matrix consisted of negative nasal swabs placed in M5 or universal transport media (UTM). The LoD is defined as the lowest concentration (tissue culture infective dose, $\mathrm{TCID}_{50} / \mathrm{mL}$ ) per sample that can be reproducibly detected $95\%$ of the times or lowest concentration at which 19 of 20 replicates were positive. Each strain was initially tested in a range finding study using serial dilutions of virus concentrations near the expected LoD in replicates of 10 per concentration of virus. LoD was determined using a dose response curve and interpolating the $\mathrm{C}_{95}$ from the plotting software interpolation function. Verification of the estimated LoD was performed using a minimum of 20 replicates per strain. Strains tested were A/Port Chalmers/1/73 (H3N2), A/New Jersey/8/76 (H1N1), B/Allen/45, and B/Florida/07/2004.
Determined LoD concentrations as well as confirmation testing statistical data are summarized in Table 2.
Table 2 - LoD Results for the Sofia Influenza A+B FIA in nasal swab matrix/VTM
| Strain | Matrix | TCID50/ml | Influenza A Positive calls | Influenza B Positive calls |
| --- | --- | --- | --- | --- |
| A/NJ | M5 | 2460 | 20/20 | 0/20 |
| | UTM | 1645 | 20/20 | 0/20 |
| A/Port Chalmers | M5 | 1482 | 19/20 | 0/20 |
| | UTM | 1446 | 20/20 | 0/20 |
| B/Allen | M5 | 5 | 0/20 | 20/20 |
| | UTM | 4.6 | 0/20 | 19/20 |
| B/Florida | M5 | 40 | 0/20 | 20/20 |
| | UTM | 35 | 0/20 | 20/20 |
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e. Analytical reactivity:
**Analytical Reactivity**
See decision summary for K112177.
f. Analytical Specificity:
See decision summary for K112177.
g. Potentially Interfering Substances:
See decision summary for K112177.
f. Assay cut-off:
The Sofia Analyzer uses a constant set of calculations to generate processed peak heights. The peak heights are used by the test method file to calculate a final test result.
2. Comparison studies:
a. Method comparison with predicate device:
N/A
b. Matrix comparison:
N/A
c. Fresh versus frozen equivalency
N/A
3. Clinical studies:
a. Clinical Sensitivity and Specificity
A prospective clinical study for Sofia Influenza A+B FIA was conducted during February through March 2011 in the United States. A total of 17 intended use clinical sites and three (3) reference laboratories participated in the study. Three (3) different specimen types, nasal swab (NS), nasopharyngeal swab (NPS), and nasopharyngeal aspirate/wash (NPA/W), were evaluated in this study. All specimen types were tested fresh and after the sample had been suspended into viral transport media (VTM) and transported to the corresponding reference
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laboratory. Testing was performed at the time of the original clinical study but data on specimens in VTM was not included in the previous submission (K112177). The data is being supplied now in order to support the specimens in VTM claim. All test results were compared to viral culture as the reference method.
A total of 2152 subject specimens were available for use in the clinical study. Of the 2152 eligible specimens, 2019 were included in the study (12 specimens had no culture data available, 55 were excluded due to site protocol deviations, 65 specimens were lost from the device SD cards, and one (1) specimen was excluded due to the instrument error). There were 28 invalid results as determined by the subject device leaving 1991 valid specimens for analysis (665 nasal swabs, 688 nasopharyngeal swabs, and 638 NA/W specimens). There were 935 specimens collected from female subjects and 1036 from male subjects. Collection and testing was performed at 17 geographically diverse locations representing intended use sites (16 sites after exclusions).
Age distribution of the patients from whom the specimens were obtained was as follows: 1410 (71%) of the specimens 5 years or younger; 439 (22%) from ages 6 to 21; 122 (6%) from ages 22 to 59; and 20 (1%) from ages 60 or older.
Sofia Influenza A+B FIA detected influenza A with a clinical sensitivity versus culture of 83%, 91% and 97% when testing nasal swab, nasopharyngeal swabs, or nasopharyngeal aspirates/washes in VTM, respectively (Table 3). The specificity ranged from 97% to 98% across all sample types.
Table 3 – Influenza A performance versus culture for all specimens in VTM
| | Nasal Swab | Nasopharyngeal Swab | Nasal Wash/Aspirate |
| --- | --- | --- | --- |
| Sensitivity | 83% (117/141) | 91% (94/103) | 97% (66/68) |
| | 95%CI (76-88%) | 95%CI (84-96%) | 95%CI (89-99%) |
| Specificity | 93% (512/524) | 98% (573/585) | 97% (553/570) |
| | 95%CI (96-99%) | 95%CI (96-99%) | 95%CI (95-98%) |
| PPV | 91% (117/129) | 89% (94/106) | 80% (66/83) |
| NPV | 96% (512/536) | 98% (573/582) | >99% (553/555) |
| Prevalence | 21% (141/665) | 15% (103/688) | 11% (68/638) |
Sofia Influenza A+B FIA detected influenza B with a clinical sensitivity versus culture of 80%, 82% and 84% when testing nasal swab, nasopharyngeal swabs, or nasopharyngeal aspirates/washes in VTM, respectively (Table 4). The specificity ranged from 97% to 99% across all sample types.
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Table 4 – Influenza B performance versus culture for all specimens in VTM
| | Nasal Swab | Nasopharyngeal Swab | Nasal Wash/Aspirate |
| --- | --- | --- | --- |
| Sensitivity | 80% (89/111) | 82% (88/107) | 84% (43/51) |
| | 95%CI (72-87%) | 95%CI (74-88%) | 95%CI (72-92%) |
| Specificity | 98% (540/554) | 99% (575/581) | 97% (567/587) |
| | 95%CI (96-99%) | 95%CI (98-99%) | 95%CI (95-98%) |
| PPV | 86% (89/103) | 94% (88/94) | 68% (43/63) |
| NPV | 96% (540/562) | 97% (575/594) | 99% (567/575) |
| Prevalence | 17% (111/665) | 16% (107/688) | 8% (51/638) |
4. Clinical cut-off:
N/A
5. Expected values/Reference range:
See decision summary for K112177.
N. Proposed Labeling:
The labeling is sufficient and it satisfies the requirements of 21 CFR Part 809.10.
O. Conclusion:
The submitted information in this premarket notification is complete and supports a substantial equivalence decision.
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