← Product Code [PSZ](/submissions/MI/subpart-d%E2%80%94serological-reagents/PSZ) · K191514

# CareStart Flu A&B Plus (K191514)

_Access Bio, Inc. · PSZ · Feb 18, 2020 · Microbiology · SESE_

**Canonical URL:** https://fda.innolitics.com/submissions/MI/subpart-d%E2%80%94serological-reagents/PSZ/K191514

## Device Facts

- **Applicant:** Access Bio, Inc.
- **Product Code:** [PSZ](/submissions/MI/subpart-d%E2%80%94serological-reagents/PSZ.md)
- **Decision Date:** Feb 18, 2020
- **Decision:** SESE
- **Submission Type:** Dual Track
- **Regulation:** 21 CFR 866.3328
- **Device Class:** Class 2
- **Review Panel:** Microbiology

## Indications for Use

The CareStart™ Flu A&B Plus is an in vitro rapid immunochromatographic assay for the qualitative detection of influenza virus type A and B nucleoprotein antigens directly from nasopharyngeal swab specimens of symptomatic patients. The test is intended for use as an aid in the rapid differential diagnosis of acute influenza type A and B viral infections. This test is intended to distinguish between influenza type A and/or B virus in a single test. This test is not intended to detect influenza type C viral antigens. Negative test results are presumptive and should be confirmed by viral 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 basis for treatment or other patient management decisions. Performance characteristics for influenza A and B were established during the 2018-2019 influenza season when influenza A/H3N2, A/H1N1pdm09, and B/Victoria were the predominant influenza viruses in circulation. When other influenza viruses are emerging, performance characteristics may vary. 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 the state or local health department for testing. Viral culture should not be attempted in these cases unless a BSL 3+ facility is available to received and culture specimens.

## Device Story

CareStart Flu A&B Plus is a rapid immunochromatographic lateral flow assay for qualitative detection of influenza A and B nucleoprotein antigens. Input: nasopharyngeal swab specimen eluted in extraction buffer. Process: extracted sample migrates through test strip; viral antigens bind to anti-influenza antibodies conjugated to indicator particles; immune complexes captured by test lines. Output: visual interpretation of colored lines (red for Flu A, blue for Flu B, purple for control) at 10 minutes. Used in clinical settings by healthcare providers. Provides rapid differential diagnosis to aid clinical decision-making; negative results require confirmatory molecular testing.

## Clinical Evidence

Prospective multi-site clinical study (n=944 evaluable) compared device to FDA-cleared molecular assay. Influenza A: 79.9% PPA, 98.4% NPA. Influenza B: 88.2% PPA, 100% NPA. Retrospective study (n=162) supplemented Influenza B data: 96.6% PPA, 97.8% NPA. Reproducibility and lot-to-lot precision studies showed 100% agreement.

## Technological Characteristics

Immunochromatographic lateral flow assay. Materials: test cassette with strip, extraction vials, swabs. Principle: antigen-antibody binding with indicator particles. Visual readout. No electronic components. Storage: 1-30°C. Includes internal control line and external positive/negative control swabs.

## Regulatory 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.

## Predicate Devices

- BD Veritor System for Rapid Detection of Flu A + B CLIA waived kit ([K180438](/device/K180438.md))

## Submission Summary (Full Text)

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>
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Food and Drug Administration
10903 New Hampshire Avenue
Silver Spring, MD 20993-0002
www.fda.gov

# 510(k) SUBSTANTIAL EQUIVALENCE DETERMINATION DECISION SUMMARY

ASSAY ONLY

## I Background Information:

A 510(k) Number

K191514

B Applicant

Access Bio, Inc.

C Proprietary and Established Names

CareStart Flu A&B Plus

D Regulatory Information

|  Product Code(s) | Classification | Regulation Section | Panel  |
| --- | --- | --- | --- |
|  PSZ | Class II | 21 CFR 866.3328 - Influenza Virus Antigen Detection Test System | MI - Microbiology  |

## II Submission/Device Overview:

A Purpose for Submission:

New device 510(k) clearance for the CareStart Flu A&B Plus

B Measurand:

Influenza A and influenza B viral nucleoprotein antigens

C Type of Test:

Qualitative Immunoassay

K191514 - Page 1 of 19

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III Intended Use/Indications for Use:

A Intended Use(s):
The CareStart Flu A&B Plus is an in vitro rapid immunochromatographic assay for the qualitative detection of influenza virus type A and B nucleoprotein antigens directly from nasopharyngeal swab specimens of symptomatic patients.

The test is intended for use as an aid in the rapid differential diagnosis of acute influenza type A and B viral infections. This test is intended to distinguish between influenza type A and/or B virus in a single test. This test is not intended to detect influenza type C viral antigens. Negative test results are presumptive and should be confirmed by viral 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 basis for treatment or other patient management decisions.

Performance characteristics for influenza A and B were established during the 2018-2019 influenza season when influenza A/H3N2 and A/H1N1pdm09, and B/Victoria were the predominant influenza viruses in circulation. When other influenza viruses are emerging, performance characteristics may vary.

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 the state or local health department for testing. Viral culture should not be attempted in these cases unless a BSL 3+ facility is available to received and culture specimens.

B Indication(s) for Use:
Same as Intended Use(s)

C Special Conditions for Use Statement(s):
Rx - For Prescription Use Only

D Special Instrument Requirements:
N/A

IV Device/System Characteristics:

A Device Description:

The CareStart Flu A&B Plus test is an immunochromatographic assay for detection of extracted influenza type A and B virus nucleoprotein antigens in nasopharyngeal swab specimens.

The assay kit consists of 20 cassettes (each cassette contains one test strip), 20 extraction vials, 20 caps, 20 swabs for the collection of nasopharyngeal specimens, and three external control swabs, two positive control swabs and one negative control swab. One of the positive control swabs contains inactivated influenza A virus dried onto the swab and the other positive control

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swab contains inactivated influenza B dried onto the swab. The negative control swab contains inactivated Streptococcus Group A dried onto the swab.

The kit may be stored at 1-30°C.

## B Principle of Operation:

The CareStart Flu A&B Plus test is based on antigen-antibody binding technology. The virus antigens are released from the specimen during the extraction step. Three drops of the extracted sample are added to the cassette that contains a testing strip. During the migration through the strip, the viral antigens bind to anti-influenza A and anti-influenza B antibodies conjugated to indicator particles. The antigen-antibody complexes migrate through the test strip and are captured by reagents on the membrane to form test lines and a control line. There are two separate test lines, one detecting influenza A antigens and one detecting influenza B antigens. The control line is formed by absorbing residual sample and serves as the internal control for the assay. The test is visually read 10 minutes after the sample is added to the cassette.

### Results Interpretation:

- The presence of two lines in the cassette, one for influenza A next to the letter “A” and one control line next to the letter “C”, indicates influenza A positive result.
- The presence of two lines in the cassette, one for influenza B next to the letter “B” and one control line next to the letter “C”, indicates influenza B positive result.
- The presence of three lines in the cassette, one for influenza A next to the letter “A”, one for influenza B next to the letter “B”, and one control line next to the letter “C”, indicates a double positive for influenza A and influenza B result.
- The presence of the control line in the cassette next to the letter “C” without any other lines indicates a negative result.
- The absence of a C line, regardless of whether any other lines are present or absent, represents an invalid result.

The sample with invalid result should be retested using the remaining sample present in the extraction vial.

## V Substantial Equivalence Information:

### A Predicate Device Name(s):

BD Veritor System for Rapid Detection of Flu A + B CLIA waived kit

### B Predicate 510(k) Number(s):

K180438

### C Comparison with Predicate(s):

|  Device & Predicate Device(s): | K191514 | K180438  |
| --- | --- | --- |
|  Device Trade Name | CareStart Flu A&B Plus | BD Veritor System for Rapid Detection of Flu A + B  |

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K191514 - Page 4 of 19
|  General Device Characteristic Similarities |  |   |
| --- | --- | --- |
|  Intended Use/Indications For Use | The CareStart Flu A&B Plus is an in vitro rapid immunochromatographic assay for the qualitative detection of influenza virus type A and B nucleoprotein antigens directly from nasopharyngeal swab specimens of symptomatic patients.

The test is intended for use as an aid in the rapid differential diagnosis of acute influenza type A and B viral infections. This test is intended to distinguish between influenza type A and/or B virus in a single test. This test is not intended to detect influenza type C viral antigens. Negative test results are presumptive and should be confirmed by viral 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 basis for treatment or other patient management decisions.

Performance characteristics for influenza A and B were established during the 2018-2019 influenza season when influenza A/H3N2 and A/H1N1pdm09, and B/Victoria were the predominant influenza viruses in circulation. When other influenza viruses are emerging, performance characteristics may vary.

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 the state or local health department for testing. Viral culture should not be attempted in these cases unless a BSL 3+ facility is | The BD Veritor System for Rapid Detection of Flu A+B is a rapid chromatographic immunoassay for the direct and qualitative detection of influenza A and B viral nucleoprotein antigens from nasal and nasopharyngeal swabs of symptomatic patients. The BD Veritor System for Rapid Detection of Flu A+B (also referred to as the BD Veritor System and BD Veritor System Flu A+B) is a differentiated test, such that influenza A viral antigens can be distinguished from influenza B viral antigens from a single processed sample using a single device. The test is to be used as an aid in the diagnosis of influenza A and B viral infections. A negative test is presumptive and it is recommended that these results be confirmed by viral culture or an FDA cleared influenza A and B molecular assay. Outside the U.S., a negative test is presumptive and it is recommended that these results be confirmed by viral culture or a molecular assay cleared for diagnostic use in the country of use. FDA has not cleared this device for use outside of the U.S. Negative test results do not preclude influenza viral infection and should not be used as the sole basis for treatment or other patient management decisions. The test is not intended to detect influenza C antigens. Performance characteristics for influenza A and B were established during January through March of 2011 when influenza viruses A/2009 H1N1, A/H3N2, B/Victoria lineage, and B/Yamagata lineage 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."  |

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K191514 - Page 5 of 19

|   | available to received and culture specimens. | 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 the 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  |
| --- | --- | --- |
|  Sample Type | Nasopharyngeal swab | Nasopharyngeal and nasal swab  |
|  Test Results | Qualitative | Same  |
|  Test Targets | Influenza A and influenza B nucleoprotein antigens | Same  |
|  Test Principle | Immunochromatographic | Same  |
|  Test Format | Lateral flow test | Same  |
|  General Device Characteristic Differences |  |   |
|  Detection format | Visual determination of presence or absence of colored line(s) for the test line(s) and a colored line on the test strip indicate the presence of influenza A and/or B antigen | An opto-electronic reader determines the line intensity at each of the spatially defined test and control line positions, interprets the results using a scoring algorithm, and reports a positive, negative or invalid result on the LCD screen based on pre-set thresholds.  |

VI Standards/Guidance Documents Referenced:

1. Food and Drug Administration, 21 CFR 866.8328: Microbiology Devices; Reclassification of Influenza Virus Antigen Detection Test Systems Intended for Use Directly with Clinical Specimens, Final Order, January 12, 2017
2. Establishing the Performance Characteristics of In Vitro Diagnostic Devices for the Detection or Detection and Differentiation of Influenza Viruses, July 15, 2011

VII Performance Characteristics (if/when applicable):

A Analytical Performance:

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# 1. Precision/Reproducibility:

A seven-member panel was used in all three precision/reproducibility studies described in the sections below. The panel was made using two virus strains. For the reproducibility study and the within laboratory repeatability study influenza A/Michigan/45/2015 (H1N1) pdm09 and influenza B/Phuket/3073/13 were used. For the lot-lo-lot reproducibility study influenza A/Perth/16/2009 and influenza B/Colorado/06/2017 were used. Each strain was diluted into Universal Transport Medium (UTM) at three different target levels: moderate positive ( $\sim 3x$  LoD), low positive ( $\sim 1x$  LoD), and high negative ( $\sim 0.1x$  LoD). Panel members were formulated with only one target present (influenza A or influenza B). Negative samples did not contain influenza virus. Simulated nasal swabs were prepared by pipetting  $25~\mu \mathrm{L}$  of sample (virus dilution) onto the head of the swab. Each swab was allowed to dry using vacuum dryer and then sealed in a desiccated pouch. The swabs were removed from the pouches prior to testing and the testing was performed according to the instructions for use.

# Within-Laboratory Repeatability

The within-laboratory precision of the CareStart Flu A&B Plus was evaluated in a study performed inhouse over 15 non-consecutive days, with two operators. One lot of devices was used to test in triplicate the seven-member panel described above.

The qualitative results from the within-laboratory precision study are summarized in Table 1 below.

Table 1. Within-Laboratory Precision Study Results

|  Sample | Operator #1 Agreement (Count) | Operator #2 Agreement (Count) | All Operators  |   |
| --- | --- | --- | --- | --- |
|   |   |   |  Agreement (Count) | 95% CI  |
|  Negative | 100% (90/90) | 100% (90/90) | 100% (180/180) | 97.9% – 100%  |
|  Flu A High Negative | 100% (90/90) | 100% (90/90) | 100% (180/180) | 97.9% – 100%  |
|  Flu A Low Positive | 100% (90/90) | 100% (90/90) | 100% (180/180) | 97.9% – 100%  |
|  Flu A Moderate Positive | 100% (90/90) | 100% (90/90) | 100% (180/180) | 97.9% – 100%  |
|  Flu B High Negative | 100% (90/90) | 100% (90/90) | 100% (180/180) | 97.9% – 100%  |
|  Flu B Low Positive | 100% (90/90) | 100% (90/90) | 100% (180/180) | 97.9% – 100%  |
|  Flu B Moderate Positive | 100% (90/90) | 100% (90/90) | 100% (180/180) | 97.9% – 100%  |

All samples tested in the within laboratory precision study demonstrated  $100\%$  agreement with the expected results.

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# Lot-to-lot Precision

The lot-to-lot precision of the CareStart Flu A&B Plus was evaluated in a study performed inhouse over three days, with three operators. Three lots of devices were used to test in triplicate the seven-member panel described above.

The qualitative results from the lot-to-lot precision study are summarized in Table 2 below.

Table 2. Lot-to-Lot Precision Study Results

|  Sample | Lot #1 Agreement (Count) | Lot #2 Agreement (Count) | Lot #3 Agreement (Count)  |
| --- | --- | --- | --- |
|  Negative | 100% (9/9) | 100% (9/9) | 100% (9/9)  |
|  Flu A High Negative | 100% (9/9) | 100% (9/9) | 100% (9/9)  |
|  Flu A Low Positive | 100% (9/9) | 100% (9/9) | 100% (9/9)  |
|  Flu A Moderate Positive | 100% (9/9) | 100% (9/9) | 100% (9/9)  |
|  Flu B High Negative | 100% (9/9) | 100% (9/9) | 100% (9/9)  |
|  Flu B Low Positive | 100% (9/9) | 100% (9/9) | 100% (9/9)  |
|  Flu B Moderate Positive | 100% (9/9) | 100% (9/9) | 100% (9/9)  |

All samples tested in the lot-to-lot precision study generated  $100\%$  agreement with the expected results.

# External Multi-Site User-to-User Reproducibility

The reproducibility of CareStart Flu A&B Plus assay was evaluated at three external sites with three operators per site (a total of nine operators) over five nonconsecutive days. The seven-member panel described above was tested in this study. The summary of results is presented in Table 3 below.

Table 3. Reproducibility by Study Site

|  Sample | Site #1 Agreement (Count) | Site #2 Agreement (Count) | Site #3 Agreement (Count) | All Sites  |   |
| --- | --- | --- | --- | --- | --- |
|   |   |   |   |  Agreement (Count) | 95% CI  |
|  Negative | 100% (45/45) | 100% (45/45) | 100% (45/45) | 100% (135/135) | 97.2% – 100%  |
|  Flu A High Negative | 100% (45/45) | 100% (45/45) | 100% (45/45) | 100% (135/135) | 97.2% – 100%  |
|  Flu A Low Positive | 100% (45/45) | 100% (45/45) | 100% (45/45) | 100% (135/135) | 97.2% – 100%  |
|  Flu A Moderate Positive | 100% (45/45) | 100% (45/45) | 100% (45/45) | 100% (135/135) | 97.2% – 100%  |

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All samples tested in the reproducibility study generated 100% agreement with the expected results.

2. Linearity:

Not applicable

3. Analytical Specificity/Interference:

Analytical Specificity (Cross-Reactivity)

A total of 43 microorganisms, including 31 bacteria and 15 viruses, were tested in the cross-reactivity study. Positive influenza swabs were prepared with either influenza A/Perth/16/2009 or influenza B/Colorado/06/2017. Viruses were diluted in UTM to approximately 2x LoD. Using a pipette, 25 µL of influenza sample and 50 µL of microorganism at the concentration presented below were applied to the swab. Negative samples did not contain influenza virus. Positive and negative swabs were tested in triplicate.

The concentrations of potentially interfering microorganisms tested and the results from the cross-reactivity study are presented in Table 4 below.

Table 4. Cross-Reactivity Study Results

|  Organism | Final Concentration Tested | Flu A Positive Replicates | Flu B Positive Replicates | Flu A/Flu B Negative Replicates  |
| --- | --- | --- | --- | --- |
|  Acinetobacter calcoaceticus | 10^{7} CFU/mL | 3/3 | 3/3 | 3/3  |
|  Adenovirus 1 | 10^{5.2} TCID_{50}/mL | 3/3 | 3/3 | 3/3  |
|  Adenovirus 7 | 10^{5.45} TCID_{50}/mL | 3/3 | 3/3 | 3/3  |
|  Bordetella pertussis | 10^{7} CFU/mL | 3/3 | 3/3 | 3/3  |
|  Candida albicans | 10^{7} CFU/mL | 3/3 | 3/3 | 3/3  |
|  Chlamydophila pneumoniae | 10^{7} CFU/mL | 3/3 | 3/3 | 3/3  |
|  Coronavirus OC43 | 10^{5.45} TCID_{50}/mL | 3/3 | 3/3 | 3/3  |
|  Coronavirus 229E | 10^{4.45} TCID_{50}/mL | 3/3 | 3/3 | 3/3  |
|  Coxsackie virus B4 | 10^{5.45} TCID_{50}/mL | 3/3 | 3/3 | 3/3  |
|  Corynebacterium diphtheriae | 10^{7} CFU/mL | 3/3 | 3/3 | 3/3  |
|  Cytomegalovirus | 10^{4.95} TCID_{50}/mL | 3/3 | 3/3 | 3/3  |
|  Enterococcus faecalis | 10^{7} CFU/mL | 3/3 | 3/3 | 3/3  |
|  Escherichia coli | 10^{7} CFU/mL | 3/3 | 3/3 | 3/3  |
|  Gardnerella vaginalis | 10^{7} CFU/mL | 3/3 | 3/3 | 3/3  |
|  Haemophilus influenzae | 10^{7} CFU/mL | 3/3 | 3/3 | 3/3  |
|  Klebsiella pneumoniae | 10^{7} CFU/mL | 3/3 | 3/3 | 3/3  |

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|  Lactobacillus casei | 10^{7} CFU/mL | 3/3 | 3/3 | 3/3  |
| --- | --- | --- | --- | --- |
|  Legionella pneumophila | 10^{7} CFU/mL | 3/3 | 3/3 | 3/3  |
|  Listeria monocytogenes | 10^{7} CFU/mL | 3/3 | 3/3 | 3/3  |
|  Measles virus | 10^{4.2} TCID_{50}/mL | 3/3 | 3/3 | 3/3  |
|  Metapneumovirus | 2.8 x 10^{5} TCID_{50}/mL | 3/3 | 3/3 | 3/3  |
|  Moraxella catarrhalis | 10^{7} CFU/mL | 3/3 | 3/3 | 3/3  |
|  Mumps virus (Enders) | 10^{5.2} TCID_{50}/mL | 3/3 | 3/3 | 3/3  |
|  Mycobacterium tuberculosis | 10^{7} CFU/mL | 3/3 | 3/3 | 3/3  |
|  Mycoplasma pneumoniae | 1.5 x 10^{3} CFU/mL | 3/3 | 3/3 | 3/3  |
|  Neisseria gonorrhoeae | 10^{7} CFU/mL | 3/3 | 3/3 | 3/3  |
|  Neisseria meningitidis | 10^{7} CFU/mL | 3/3 | 3/3 | 3/3  |
|  Neisseria sicca | 10^{7} CFU/mL | 3/3 | 3/3 | 3/3  |
|  Parainfluenza virus 1 | 10^{5.86} TCID_{50}/mL | 3/3 | 3/3 | 3/3  |
|  Parainfluenza virus 2 | 10^{5.2} TCID_{50}/mL | 3/3 | 3/3 | 3/3  |
|  Parainfluenza virus 3 | 10^{5.2} TCID_{50}/mL | 3/3 | 3/3 | 3/3  |
|  Proteus vulgaris | 10^{7} CFU/mL | 3/3 | 3/3 | 3/3  |
|  Pseudomonas aeruginosa | 10^{7} CFU/mL | 3/3 | 3/3 | 3/3  |
|  Respiratory Syncytial Virus B | 10^{5.2} TCID_{50}/mL | 3/3 | 3/3 | 3/3  |
|  Rhinovirus 1A | 10^{5.2} TCID_{50}/mL | 3/3 | 3/3 | 3/3  |
|  Rubella | 10^{5.2} TCID_{50}/mL | 3/3 | 3/3 | 3/3  |
|  Staphylococcus aureus | 10^{7} CFU/mL | 3/3 | 3/3 | 3/3  |
|  Staphylococcus epidermidis | 10^{7} CFU/mL | 3/3 | 3/3 | 3/3  |
|  Serratia marcescens | 10^{7} CFU/mL | 3/3 | 3/3 | 3/3  |
|  Streptococcus mutans | 10^{7} CFU/mL | 3/3 | 3/3 | 3/3  |
|  Streptococcus pneumoniae | 10^{7} CFU/mL | 3/3 | 3/3 | 3/3  |
|  Streptococcus pyogenes | 10^{7} CFU/mL | 3/3 | 3/3 | 3/3  |
|  Streptococcus sp. Group B | 10^{7} CFU/mL | 3/3 | 3/3 | 3/3  |
|  Streptococcus sp. Group C | 10^{7} CFU/mL | 3/3 | 3/3 | 3/3  |
|  Streptococcus sp. Group F | 10^{7} CFU/mL | 3/3 | 3/3 | 3/3  |
|  Streptococcus sanguinis | 10^{7} CFU/mL | 3/3 | 3/3 | 3/3  |

The study results showed no cross-reactivity of the above listed microorganisms with the CareStart Flu A&B Plus assay at the concentrations tested. All influenza negative samples gave negative results. In addition, all influenza A and influenza B samples tested positive in the presence of the above listed microorganisms showing no interference at the concentrations tested.

## Competitive Interference

The study was performed to evaluate if the CareStart Flu A&B Plus assay can detect low levels of influenza A in the presence of high levels of influenza B and vice versa. Four influenza strains were used in this study: influenza A/Perth/16/2009, influenza A/Michigan/45/2015, influenza B/Colorado/06/2017, and influenza B/Phuket/3073/2013. For low concentration samples, influenza strains were diluted to approximately 1x LoD and for the high concentrations 5-fold dilutions of the virus stock were used. Using a pipette, 50 µL of each influenza sample was applied to a swab. The swabs were tested in triplicate. Low and high concentrations of the influenza strains used in this study are presented in Table 5 below.

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Table 5. Influenza Strains and Concentrations Tested

|  Influenza stain | Low concentration | High concentration  |
| --- | --- | --- |
|  A/Perth/16/2009 | 3.2 x 10^{4.9} EID_{50}/mL | 2.0 x 10^{7.9} EID_{50}/mL  |
|  A/Michigan/45/2015 | 3.2 x 10^{4.2} EID_{50}/mL | 2.0 x 10^{7.2} EID_{50}/mL  |
|  B/Colorado/06/2017 | 1.6 x 10^{6.4} EID_{50}/mL | 2.0 x 10^{8.4} EID_{50}/mL  |
|  B/Phuket/3073/2013 | 1.6 x 10^{5.5} EID_{50}/mL | 2.0 x 10^{7.5} EID_{50}/mL  |

The results of the competitive interference study are summarized in Table 6 below.

Table 6. Competitive Interference Study Results

|  Influenza A strain | Influenza B strain | Influenza A Positive Replicates | Influenza B Positive Replicates  |
| --- | --- | --- | --- |
|  A/Perth/16/2009
Low concentration | B/Colorado/06/2017
High concentration | 3/3 | 3/3  |
|  A/Perth/16/2009
Low concentration | B/Phuket/3073/2013
High concentration | 3/3 | 3/3  |
|  A/Michigan/45/2015
Low concentration | B/Colorado/06/2017
High concentration | 3/3 | 3/3  |
|  A/Michigan/45/2015
Low concentration | B/Phuket/3073/2013
High concentration | 3/3 | 3/3  |
|  A/Perth/16/2009
High concentration | B/Colorado/06/2017
Low concentration | 3/3 | 3/3  |
|  A/Perth/16/2009
High concentration | B/Phuket/3073/2013
Low concentration | 3/3 | 3/3  |
|  A/Michigan/45/2015
High concentration | B/Colorado/06/2017
Low concentration | 3/3 | 3/3  |
|  A/Michigan/45/2015
High concentration | B/Phuket/3073/2013
Low concentration | 3/3 | 3/3  |

The study results showed that CareStart Flu A&B Plus assay can detect low levels of influenza A in the presence of high levels of influenza B and low levels of influenza B in the presence of high levels of influenza A.

## Potentially interfering substances

Positive influenza swabs were prepared for four viral strains: influenza A/Perth/16/2009, influenza A/Michigan/45/2015, influenza B/Colorado/06/2017, and influenza B/Phuket/3073/2013. Viruses were diluted in UTM to approximately 2x LoD and the potentially interfering substance was spiked to the concentration presented in the table below. The swabs were prepared by pipetting 50 µL of sample to the swab. The negative swabs contained UTM and potentially interfering substance only. Positive and negative samples were tested in triplicate.

The concentrations of potentially interfering substances tested and the results from the interference study are presented in Table 7 below.

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Table 7. Interference Study Results

|  Interfering Substance | Concentration Tested | Influenza A Positive Replicates |   | Influenza B Positive Replicates |   | Negative Samples  |
| --- | --- | --- | --- | --- | --- | --- |
|   |   |  A/Perth/16/2009 | A/Michigan/45/2015 | B/Colorado/06/2017 | B/Phuket/3073/2013  |   |
|  Acetaminophen | 10 mg/mL | 3/3 | 3/3 | 3/3 | 3/3 | 0/3  |
|  Acetyl salicylic acid | 15 mg/mL | 3/3 | 3/3 | 3/3 | 3/3 | 0/3  |
|  Beclomethasone | 0.5 mg/mL | 3/3 | 3/3 | 3/3 | 3/3 | 0/3  |
|  Benzocaine | 5 mg/mL | 3/3 | 3/3 | 3/3 | 3/3 | 0/3  |
|  Budesonide | 2 mg/mL | 3/3 | 3/3 | 3/3 | 3/3 | 0/3  |
|  Chlorpheniramine maleate | 5 mg/mL | 3/3 | 3/3 | 3/3 | 3/3 | 0/3  |
|  Dexamethasone | 1 mg/mL | 3/3 | 3/3 | 3/3 | 3/3 | 0/3  |
|  Dextromethorphan HBr | 2 mg/mL | 3/3 | 3/3 | 3/3 | 3/3 | 0/3  |
|  Diphenhydramine HCl | 5 mg/mL | 3/3 | 3/3 | 3/3 | 3/3 | 0/3  |
|  Ephedrine HCl | 10 mg/mL | 3/3 | 3/3 | 3/3 | 3/3 | 0/3  |
|  Flunisolide | 5 mg/mL | 3/3 | 3/3 | 3/3 | 3/3 | 0/3  |
|  Fluticasone | 1 mg/mL | 3/3 | 3/3 | 3/3 | 3/3 | 0/3  |
|  Guaiacol Glyceryl Ether | 20 mg/mL | 3/3 | 3/3 | 3/3 | 3/3 | 0/3  |
|  Histamine Dihydrochloride | 10 mg/mL | 3/3 | 3/3 | 3/3 | 3/3 | 0/3  |
|  Menthol | 10 mg/mL | 3/3 | 3/3 | 3/3 | 3/3 | 0/3  |
|  Mometasone | 1 mg/mL | 3/3 | 3/3 | 3/3 | 3/3 | 0/3  |
|  Mucin | 2% | 3/3 | 3/3 | 3/3 | 3/3 | 0/3  |
|  Mupirocin | 1 mg/mL | 3/3 | 3/3 | 3/3 | 3/3 | 0/3  |
|  OTC Throat drop (Halls) | 15% | 3/3 | 3/3 | 3/3 | 3/3 | 0/3  |
|  OTC Throat drop (Ricola) | 15% | 3/3 | 3/3 | 3/3 | 3/3 | 0/3  |
|  OTC Nasal spray (Afrin) | 15% | 3/3 | 3/3 | 3/3 | 3/3 | 0/3  |
|  OTC Nasal spray (Vicks Sinex) | 15% | 3/3 | 3/3 | 3/3 | 3/3 | 0/3  |
|  OTC Nasal spray (Zicam) | 15% | 3/3 | 3/3 | 3/3 | 3/3 | 0/3  |
|  Oxymetazoline HCl | 10 mg/ml | 3/3 | 3/3 | 3/3 | 3/3 | 0/3  |
|  Phenylephrine HCl | 5 mg/ml | 3/3 | 3/3 | 3/3 | 3/3 | 0/3  |
|  Phenylpropanol-amine | 5 mg/ml | 3/3 | 3/3 | 3/3 | 3/3 | 0/3  |
|  Tobramycin | 1 mg/ml | 3/3 | 3/3 | 3/3 | 3/3 | 0/3  |
|  Triamcinolone | 1 mg/ml | 3/3 | 3/3 | 3/3 | 3/3 | 0/3  |
|  Whole Blood | 2% | 3/3 | 3/3 | 3/3 | 3/3 | 0/3  |
|  Zanamivir | 1 mg/ml | 3/3 | 3/3 | 3/3 | 3/3 | 0/3  |

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The study results showed no interference with positive or negative results for the CareStart Flu A&B Plus assay at the concentrations tested in the presented study.

## Biotin Interference

Positive influenza swabs were prepared for four viral strains: influenza A/Perth/16/2009, influenza A/Michigan/45/2015, influenza B/Colorado/06/2017, and influenza B/Phuket/3073/2013. Viruses were diluted in UTM to approximately 2x LoD and biotin was spiked to the levels presented in the table below. The swabs were prepared by pipetting 50 μL of sample to the swab. The negative swabs contained UTM and biotin only. Positive and negative samples were tested in triplicate.

The results from the biotin interference study are summarized in Table 8 below.

Table 8. Biotin Interference Study Results

|  Biotin Concentration Tested | Influenza A Positive Replicates |   | Influenza B Positive Replicates |   | Negative Samples  |
| --- | --- | --- | --- | --- | --- |
|   |  A/Perth/16/2009 | A/Michigan/45/2015 | B/Colorado/06/2017 | B/Phuket/3073/2013  |   |
|  2 μg/mL | 0/3 | 0/3 | 3/3 | 3/3 | 0/3  |
|  1 μg/mL | 0/3 | 0/3 | 3/3 | 3/3 | 0/3  |
|  500 ng/mL | 3/3 | 3/3 | 3/3 | 3/3 | 0/3  |
|  250 ng/mL | 3/3 | 3/3 | 3/3 | 3/3 | 0/3  |
|  200 ng/mL | 3/3 | 3/3 | 3/3 | 3/3 | 0/3  |
|  125 ng/mL | 3/3 | 3/3 | 3/3 | 3/3 | 0/3  |

Biotin concentrations up to 500 ng/mL did not lead to false results. Biotin concentrations >500 ng/mL may cause false negative influenza A results with the CareStart Flu A&B Plus. Due to the relatively high level of biotin tolerance and the specimen type, which is unlikely to have biotin concentrations as high as what is observed in serum/plasma specimens, no limitation in the labeling regarding the biotin interference was necessary.

4. Assay Reportable Range:

Not applicable.

5. Traceability, Stability, Expected Values (Controls, Calibrators, or Methods):

## Internal Quality Control

The CareStart Flu A&B Plus assay contains built in internal assay control. The control line contains control antibodies which bind residual sample. The appearance of the control line on the test ensures that sufficient flow of the sample occurred during the assay.

## External Quality Controls

The CareStart Flu A&B Plus kit contains two positive external control swabs (one for influenza A and one for influenza B) and one negative external control swab that allow for

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monitoring of the performance of the assay. Influenza A positive external control contains inactivated influenza A virus, influenza B positive external control contains inactivated influenza B virus. Negative control swab contains inactivated Streptococcus sp. Group A.

## External Controls Lot-to-Lot Reproducibility

The lot-to-lot reproducibility for the external positive and negative control swabs was evaluated using three lots of external controls with three operators. The results from the study are summarized in Table 9 below.

Table 9. External Controls Lot-to-Lot Reproducibility Study Results

|  Lot No. | Influenza A Positive Control Results Agreement (Count) | Influenza B Positive Control Results Agreement (Count) | Negative Control Results Agreement (Count)  |
| --- | --- | --- | --- |
|  1 | 100%
(9/9) | 100%
(9/9) | 100%
(9/9)  |
|  2 | 100%
(9/9) | 100%
(9/9) | 100%
(9/9)  |
|  3 | 100%
(9/9) | 100%
(9/9) | 100%
(9/9)  |

All lots of external controls generated 100% agreement with the expected results.

## 6. Detection Limit:

The limit of detection (LoD) of the assay was determined with four strains of influenza A virus and four strains of influenza B virus in three step process. First, the initial LoD range was established using a series of five-fold dilutions of virus stocks prepared in UTM. Using a pipette, 50 μL of each dilution was applied to a swab. The swabs were tested in triplicate. The lowest concentration that resulted in 100% detection (3/3) was used to test 20 replicates. The dilution that resulted in ≥95% detection was considered initial LoD range. In the next step, a series of two-fold dilutions in negative nasal matrix near the initial LoD range were prepared. Using a pipette, 50 μL of each dilution were applied to a swab and tested in triplicate until a negative result was obtained for at least one of the replicates. The estimated LoD was confirmed by testing 20 replicates. The results from the study are presented in Table 10 below.

Table 10. Limit of Detection (LoD)

|  Influenza virus type/subtype | Strain | LoD (EID_{50}/mL)^{1} | Percent Positive Results (# positive/# tested)  |
| --- | --- | --- | --- |
|  A (H3N2) | A/Perth/16/2009 | 3.2 x 10^{4.9} | 100% (20/20)  |
|   |  A/Singapore/INFIMH-16-0019/2016 | 2.0 x 10^{5.2} | 100% (20/20)  |
|  A (H1N1) pdm09 | A/California/07/2009 | 3.2 x 10^{4.9} | 100% (20/20)  |
|   |  A/Michigan/45/2015 | 3.2 x 10^{4.2} | 100% (20/20)  |
|  B (Victoria lineage) | B/Brisbane/60/2008 | 2.0 x 10^{5.5} | 100% (19/20)  |
|   |  B/Colorado/06/2017 | 1.6 x 10^{6.4} | 100% (20/20)  |

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|  B (Yamagata lineage) | B/Wisconsin/01/2010 | 4.0 x 10^4.9 | 100% (20/20)  |
| --- | --- | --- | --- |
|   |  B/Phuket/3073/2013 | 1.6 x 10^5.5 | 100% (20/20)  |

$^{1}\mathrm{EID}_{50} = 50\%$  Egg Infectious Dose

# 7. Analytical Reactivity (Inclusivity)

A total of 15 influenza A strains and 10 influenza B strains were tested in the inclusivity study. 10-fold dilutions of virus stocks were prepared in UTM and  $50~\mu \mathrm{L}$  were pipetted onto the swabs. The swabs were tested in triplicate in this study. The lowest dilution of each strain that resulted in  $100\%$  detection (3/3) is presented in Table 11 below.

Table 11. Analytical Reactivity

|  Subtype | Influenza Strain | Concentration tested | Flu A Positive Replicates | Flu B Positive Replicates  |
| --- | --- | --- | --- | --- |
|  A (H3N2) | A/Alaska/232/2015 | 2.6 x 10^6 CEID50/mL | 3/3 | 0/3  |
|   |  A/California/02/2014 | 5.8 x 10^2 TCID50/mL | 3/3 | 0/3  |
|   |  A/Hong Kong/4801/2014 | 9.6 x 10^5 CEID50/mL | 3/3 | 0/3  |
|   |  A/Michigan/15/2014 | 9.3 x 10^4 FFU/mL | 3/3 | 0/3  |
|   |  A/Texas/71/2017 | 9.3 x 10^4 FFU/mL | 3/3 | 0/3  |
|  A (H3N2)v | A/Indiana/08/2011 | 8.1 x 10^2 TCID50/mL | 3/3 | 0/3  |
|   |  A/Minnesota/11/2010 | 2.2 x 10^4 CEID50/mL | 3/3 | 0/3  |
|  A (H1N1) pdm09 | A/Bangladesh/3002/2015 | 1.3 x 10^5 CEID50/mL | 3/3 | 0/3  |
|   |  A/Dominican Republic/7293/2013 | 5.0 x 10^3 TCID50/mL | 3/3 | 0/3  |
|   |  A/Iowa/53/2015 | 2.9 x 10^6 CEID50/mL | 3/3 | 0/3  |
|   |  A/Massachusetts/15/2013 | 1.6 x 10^6 CEID50/mL | 3/3 | 0/3  |
|   |  A/Michigan/272/2017 | 9.6 x 10^3 TCID50/mL | 3/3 | 0/3  |
|   |  A/New Hampshire/02/2010 | 1.8 x 10^6 CEID50/mL | 3/3 | 0/3  |
|   |  A/South Carolina/2/2010 | 2.5 x 10^5 CEID50/mL | 3/3 | 0/3  |
|   |  A/St. Petersburg/61/2015 | 9.3 x 10^5 CEID50/mL | 3/3 | 0/3  |
|  B (Victoria lineage) | B/New Jersey/1/2012 | 8.8 x 10^4 TCID50/mL | 0/3 | 3/3  |
|   |  B/Colorado/6/2017 | 1.6 x 10^6 CEID50/mL | 0/3 | 3/3  |
|   |  B/Florida/78/2015 | 1.7 x 10^6 CEID50/mL | 0/3 | 3/3  |
|   |  B/Hong Kong/286/2017 | 2.7 x 10^3 TCID50/mL | 0/3 | 3/3  |
|   |  B/Maryland/15/2016 | 1.3 x 10^3 TCID50/mL | 0/3 | 3/3  |
|  B (Yamagata lineage) | B/Guangdong-Liwan/1133/2014 | 1.8 x 10^6 CEID50/mL | 0/3 | 3/3  |
|   |  B/Massachusetts/2/2012 | 1.0 x 10^7 CEID50/mL | 0/3 | 3/3  |
|   |  B/Phuket/3073/2013 | 1.1 x 10^6 CEID50/mL | 0/3 | 3/3  |
|   |  B/Texas/06/2011 | 6.2 x 10^6 CEID50/mL | 0/3 | 3/3  |
|   |  B/Utah/09/2014 | 6.3 x 10^4 CEID50/mL | 0/3 | 3/3  |

# 8. Assay Cut-Off:

Not applicable

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# B Comparison Studies:

# 1. Method Comparison with Predicate Device:

Not applicable. Performance of the CareStart Flu A&B Plus was evaluated in a clinical study against an FDA-cleared molecular assay.

# 2. Matrix Comparison:

# Matrix Equivalency

Matrix equivalency study was conducted to determine if UTM can be used as a substitute to natural negative clinical matrix in analytical studies performed to evaluate the CareStart Flu A&B Plus assay. Influenza A/Michigan/45/2015 and influenza B/Colorado/06/2017 were diluted in natural nasal swab matrix or UTM. The pooled natural matrix was prepared by eluting nasal swabs in  $3\mathrm{mL}$  of UTM and combing matrix obtained from 17 healthy volunteers. The negativity for influenza A and B of the pooled matrix was confirmed by testing with an FDA-cleared molecular assay. The swabs were prepared by pipetting  $50~\mu \mathrm{L}$  of sample onto each swab. A series of 5-fold dilutions of each influenza strain were tested in triplicate until at least one negative result was obtained. The lowest dilution that generated  $100\%$  positive results (3/3) was confirmed by testing 20 replicates. The results from the matrix equivalency study are presented in Table 12 below.

Table 12. Matrix Equivalency Study Results

|  Influenza virus type/subtype | Matrix | LoD (EID50/mL) | Percent Positive Results (# positive/# tested)  |
| --- | --- | --- | --- |
|  A (H1N1) pdm09 | Clinical matrix | 3.2 x 104.2 | 100% (20/20)  |
|  A/Michigan/45/2015 | UTM | 3.2 x 104.2 | 100% (20/20)  |
|  B (Victoria lineage) | Clinical matrix | 1.6 x 106.4 | 100% (19/20)  |
|  B/Colorado/06/2017 | UTM | 1.6 x 106.4 | 100% (20/20)  |

The results of the study support equivalency between the clinical matrix and the Universal Transport Media (UTM) for preparation of samples for the analytical studies and the reproducibility study.

# C Clinical Studies:

# 1. Clinical Sensitivity and Specificity

Clinical performance characteristics of the CareStart Flu A&B Plus were evaluated in a multi-center prospective clinical study in the U.S. during 2018-2019 influenza season. A total of 10 clinical sites representing point-of-care participated in the study. To participate in the clinical study, the patients had to show flu-like symptoms, meet other inclusion criteria and sign informed consent. Demographics of the patients who participated in the clinical study are presented in Table 13 below.

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Table 13. Demographics of Clinical Study Participants

|  Age group | Number | Percent of Patients  |
| --- | --- | --- |
|  ≤ 5 years | 174 | 18.4%  |
|  6 to 21 years | 333 | 35.3%  |
|  22 to 59 years | 394 | 41.7%  |
|  ≥ 60 years | 43 | 4.6%  |
|  Total | 944 | 100%  |
|  Sex | Number | Percent of Patients  |
|  Male | 409 | 43.3%  |
|  Female | 535 | 56.7%  |
|  Total | 944 | 100%  |

The performance of the CareStart Flu A&B Plus assay was evaluated against an FDA-cleared molecular assay. Two nasopharyngeal swabs were collected from the same nostril of each patient participating in the clinical study. The first swab was tested with an FDA-cleared molecular assay and the second swab was tested with the CareStart Flu A&B Plus. The discrepant results were further analyzed by testing with an alternative FDA-cleared molecular assay. The performance estimates for influenza A and B compared to an FDA-cleared molecular assay are presented in Tables 14-15 below. The results of discrepant analyses are presented as footnotes and were not included in the calculation of the performance estimates.

Table 14. Performance of the CareStart Flu A&B Plus for Influenza A

|  CareStart Flu A&B Plus | Molecular Comparator  |   |   |
| --- | --- | --- | --- |
|   | Positive | Negative | Total  |
|  Positive | 307 | 9a | 316  |
|  Negative | 77b | 551 | 628  |
|  Total | 384 | 560 | 944  |
|  Sensitivity: 79.9% (95% CI: 75.7% – 83.7%)  |   |   |   |
|  Specificity: 98.4% (95% CI: 97.0% – 99.2%)  |   |   |   |

a Influenza A was detected in 2/9 false positive specimens using an alternative FDA-cleared molecular influenza A/B assay
b Influenza A was not detected in 15/77 false negative specimens using an alternative FDA-cleared molecular influenza A/B assay

Table 15. Performance of the CareStart Flu A&B Plus for Influenza B (Prospectively Collected Specimens)

|  CareStart Flu A&B Plus | Molecular Comparator  |   |   |
| --- | --- | --- | --- |
|   | Positive | Negative | Total  |
|  Positive | 15 | 0 | 15  |
|  Negative | 2a | 927 | 929  |
|  Total | 17 | 927 | 944  |
|  Sensitivity: 88.2% (95% CI: 65.7% – 96.7%)  |   |   |   |
|  Specificity: 100.0% (95% CI: 99.6% – 100.0%)  |   |   |   |

a Influenza B was detected in 2/2 false negative specimens using an alternative FDA-cleared molecular influenza A/B assay

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Due to the low prevalence of influenza B during 2018-2019 flu season in the U.S., additional archived specimens were tested with CareStart Flu A&B Plus assay. A total of 162 swabs (112 samples positive for influenza B and 50 negative samples) prepared from archived frozen respiratory specimens were tested with CareStart Flu A&B Plus assay and an FDA-cleared molecular assay. The performance estimates for the archived specimens are presented in Table 16 below.

Table 16. Performance of the CareStart Flu A&B Plus for Influenza B (Archived Specimens)

|  CareStart Flu A&B Plus | Molecular Comparator  |   |   |
| --- | --- | --- | --- |
|   | Positive | Negative | Total  |
|  Positive | 113 | 1 | 114  |
|  Negative | 4 | 44 | 48  |
|  Total | 117 | 45 | 162  |
|  Sensitivity: 96.6% (95% CI: 91.5% – 98.7%)  |   |   |   |
|  Specificity: 97.8% (95% CI: 88.4% – 99.6%)  |   |   |   |

Performance of the CareStart Flu A&B Plus against the molecular comparator (percent agreement) by the age group for influenza A is presented in Table 17 below.

Table 17. Performance of the CareStart Flu A&B Plus for Influenza A Stratified by Age Group

|  Age group | Influenza A Sensitivity 95% CI | Influenza A Specificity 95% CI  |
| --- | --- | --- |
|  ≤ 5 years | 83.3% (55/66) | 94.4% (102/108)  |
|   |  72.6% – 90.4% | 88.4% – 97.4%  |
|  6 to 21 years | 82.5% (141/171) | 98.8% (160/162)  |
|   |  76.1% – 87.4% | 95.6% – 99.7%  |
|  22 to 59 years | 74.1% (100/135) | 99.6% (258/259)  |
|   |  66.1% – 80.7% | 97.8% – 99.9%  |
|  ≥60 years | 91.7% (11/12) | 100% (31/31)  |
|   |  64.6% – 98.5% | 89.0% – 100.0%  |

Performance of the CareStart Flu A&B Plus against the molecular comparator (percent agreement) by the age group for influenza B prospectively collected specimens is presented in Table 18 below.

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Table 18. Performance of the CareStart Flu A&B Plus for Influenza B (Prospectively Collected Specimens) Stratified by Age Group

|  Age group | Influenza B Sensitivity 95% CI | Influenza B Specificity 95% CI  |
| --- | --- | --- |
|  ≤ 5 years | 100% (2/2)
34.2% – 100% | 100% (172/172)
97.8% – 100%  |
|  6 to 21 years | 87.5% (7/8)
52.9% – 97.8% | 100% (325/325)
98.8% – 100%  |
|  22 to 59 years | 83.3% (5/6)
43.7% – 97.0% | 100% (388/388)
99.0% – 100%  |
|  ≥60 years | 100% (1/1)
20.7% – 100% | 100% (42/42)
91.6% – 100%  |

D Clinical Cut-Off:

Not applicable

E Expected Values/Reference Range:

In the CareStart Flu A&B Plus prospective clinical study performed during 2018-2019 influenza season, a total of 944 nasopharyngeal swabs were evaluated. The number of positives and positivity rate of influenza A and influenza B specimens per age group are presented in Tables 19-20 below.

Table 19. Influenza A Positives by CareStart Flu A&B Plus

|  Age group | Number of Specimens | Number of Influenza A Positives | Influenza A Positivity Rate  |
| --- | --- | --- | --- |
|  ≤ 5 years | 174 | 61 | 35.1%  |
|  6 to 21 years | 333 | 143 | 42.9%  |
|  22 to 59 years | 394 | 101 | 25.6%  |
|  ≥60 years | 43 | 11 | 25.6%  |
|  Total | 944 | 316 | 33.5%  |

Table 20. Influenza B Positives by CareStart Flu A&B Plus

|  Age group | Number of Specimens | Number of Influenza B Positives | Influenza B Positivity Rate  |
| --- | --- | --- | --- |
|  ≤ 5 years | 174 | 2 | 1.5%  |
|  6 to 21 years | 333 | 7 | 2.1%  |
|  22 to 59 years | 394 | 5 | 1.3%  |
|  ≥60 years | 43 | 1 | 2.3%  |
|  Total | 944 | 15 | 1.6%  |

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VIII Proposed Labeling:

The labeling supports the finding of substantial equivalence for this device.

IX Conclusion:

The submitted information in this premarket notification is complete and supports a substantial equivalence decision.

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**Source:** [https://fda.innolitics.com/submissions/MI/subpart-d%E2%80%94serological-reagents/PSZ/K191514](https://fda.innolitics.com/submissions/MI/subpart-d%E2%80%94serological-reagents/PSZ/K191514)

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