For the qualitative and semi-quantitative detection of IgG antibodies to Varicella-Zoster Virus (VZV) in human serum by indirect immunoassay to determine a prior exposure to VZV and, when evaluating paired sera, to aid in the determination of acute or convalescent stage of VZV infection. These reagents can be used either manually or in conjunction with the MAGO® Plus Automated EIA Processor.
Device Story
Is-VZV IgG Test System is an enzyme-linked immunosorbent assay (EIA) for detecting IgG antibodies to VZV in human serum; utilizes microtiter wells coated with partially purified VZV antigen. Procedure involves adding patient serum; washing; adding enzyme-labeled anti-human immunoglobulin conjugate; washing; and adding substrate. Color intensity measured photometrically provides indirect measure of specific antibody levels. Used in clinical laboratories; performed manually or via MAGO Plus Automated EIA Processor. Results aid clinicians in determining prior VZV exposure or assessing infection stage via paired sera analysis. Benefits include standardized semi-quantitation of immune status.
Clinical Evidence
Bench testing only. Evaluated 652 serum samples across three sites comparing manual and MAGO Plus automated methods against other commercial EIA kits. Results showed relative sensitivity ranging from 97.6% to 99.4% and relative specificity from 93.1% to 100.0%. Overall agreement ranged from 97.6% to 99.5%. Precision studies (intra- and inter-assay) and linearity (20-100 EU/ml) were performed. No cross-reactivity observed with HSV, Measles, Rubella, or CMV IgG.
Technological Characteristics
Enzyme-linked immunosorbent assay (EIA) using microtiter plates coated with partially purified VZV antigen. Photometric detection of color intensity. Compatible with manual processing or MAGO Plus Automated EIA Processor. Reportable range 20-100 EU/ml.
Indications for Use
Indicated for qualitative and semi-quantitative detection of IgG antibodies to VZV in human serum to determine prior exposure or aid in identifying acute/convalescent stages of VZV infection.
Regulatory Classification
Identification
Varicella-zoster virus serological reagents are devices that consist of antigens and antisera used in serological tests to identify antibodies to varicella-zoster in serum. The identification aids in the diagnosis of diseases caused by varicella-zoster viruses and provides epidemiological information on these diseases. Varicella (chicken pox) is a mild, highly infectious disease, chiefly of children. Zoster (shingles) is the recurrent form of the disease, occurring in adults who were previously infected with varicella-zoster viruses. Zoster is the response (characterized by a rash) of the partially immune host to a reactivation of varicella viruses present in latent form in the patient's body.
Predicate Devices
Diamedix VZVMicroassay
Submission Summary (Full Text)
{0}------------------------------------------------
#### SEP 2 8 1998 510(k) Summary of Safety and Effectiveness
This summary of 510(k) safety and effectiveness information is being submitted in accordance with the requirements of SMDA 1990 and 21 CFR 807.92.
The assigned 510(k) number is:
#### Applicant Information:
| Date Prepared: | July 21, 1998 |
|----------------|-----------------------------------------|
| Name: | Diamedix Corporation |
| Address: | 2140 N. Miami Avenue<br>Miami, FL 33127 |
| Contact Person: | Dr. Lynne Stirling |
|-----------------|--------------------|
| Phone Number: | 305-324-2354 |
| Fax Number: | 305-324-2585 |
#### Device Information:
Trade Name: Is-VZV IgG Test System VZV EIA Test Common Name: Classification Name: Enzyme linked immunosorbent assay, varicella zoster virus
#### Equivalent Device:
)
Diamedix VZVMicroassay
Device Description: The Is-VZV IgG Test System is an enzyme immunoassay (EIA) for the detection and semi-quantitation of IgG antibodies to VZV antigen in human serum
Intended Use: The assay is intended for use in detecting IgG antibodies to VZV antigen in human serum. The results of the assay can be used to determine a prior exposure to VZV and, when evaluating paired sera, to aid in the determination of acute or convalescent stage of VZV infection.
#### Principle of the Procedure:
The Is-VZV IgG Test System is an enzyme-linked immunosorbent assay to detect IgG to VZV in human serum. Partially purified VZV antigen is attached to a solid phase microtiter well. Diluted test sera are added to each well. If antibodies which recognize the VZV antigen are present in the patient sample they will bind to the antigen on the well. After incubation, the wells are washed to remove unbound antibody. An enzyme labeled anti-human immunoglobulin (conjugate) is added to each test well. If antibody is present the enzyme-linked antibody will bind to it. After incubation, the wells are washed to remove unbound conjugate. A substrate solution is then added to each well. If enzyme is present from the prior step, the reaction is stopped and the color intensity is measured photometrically producing an indirect measure of the specific antibody present in the patient sample.
{1}------------------------------------------------
# SUMMARY OF SAFETY AND EFFECTIVEN
## Performance Characteristics
## АТТАСНМ
#### A. Comparison Testing
A total of six hundred and fifty-two sera were tested for the presence of VZV IgG antibodies using the Diamedix Is-VZV IgG Test Kit and another commercially available EIA test kit at two independent sites (site #1, Miami, FL and site #2, Salt Lake City, Utah) as well as at Diamedix Corp., Miami FL (site #3). At site #3, testing was performed both manually and using the MAGO Plus Automated EIA processor.
Site #1 tested 200 sera (all frozen). Samples were obtained from the S. Florida area. Thirty-seven of the samples were obtained from males, including 5 children, and ninety-seven from females. Of the 97 samples from females, 46 (47%) were of child-bearing age (18-45 years). No age or gender data was available on the remaining samples. Table 1 compares the results obtained for the Is-VZV IgG Test Kit and their currently used testing method.
Site #2 tested 198 sera (all fresh). Samples were obtained from the Mid-West region. Fifty-eight of the samples were obtained from males, including 6 children, and one hundred and twenty-seven from females, including one child. Of the 127 samples from females, 107 (84%) were of child-bearing age (18-45 years). No age or gender data was available on the remaining samples. Table 2 compares the results obtained for the Is-VZV IgG Test Kit and their currently used testing method.
| TABLE 1<br>Is-VZV IgG : Site #1 | | | TABLE 2<br>Is-VZV IgG : Site #2 | | | |
|---------------------------------------------------------------------------------------------------------------------------------------------------------------|----------|----------|-----------------------------------------------------------------------------------------------------------------------------------------------------------|----------|----------|-----------|
| | Positive | Negative | Equivocal | Positive | Negative | Equivocal |
| Positive | 171 | 1 | 3 | 164 | 4 | 6 |
| Other<br>EIA<br>Negative | 0 | 23 | 2 | 0 | 19 | 2 |
| Equivocal | 0 | 0 | 0 | 0 | 3 | 0 |
| 95%CI**<br>Relative Sensitivity 171/172 = 99.4% 96.8-100.0<br>Relative Specificity 23/23 = 100.0% 85.2-100.0<br>Overall Agreement* 194/195 = 99.5% 97.2-100.0 | | | 95%CI*<br>Relative Sensitivity 164/168 = 97.6% 94.0-99.3<br>Relative Specificity 19/19 = 100.0% 82.4-100.0<br>Overall agreement 183/187 = 97.9% 94.6-99.4 | | | |
*Equivocal results were excluded from calculations
** Calculated by the Exact Method (10).
For site #1, the discordant sample was equivocal when tested by a referee EIA method. For site #2, the discordant sera were not available for further resolution.
Site #3 (Diamedix Corp.) tested 254 samples (all frozen) by the manual method and 253 of these samples (one being QNS) by the MAGO Plus method. No age or gender data was available for these samples. Of the samples tested 74 were specifically selected either because they were negative or had values close to the cut-off by other EIA methods. The remainder of the samples were obtained from the normal S. Florida blood donor population. Tables 3 and 4 compare the results obtained by manual and MAGO Plus testing for the Is-VZV IgG Test Kit and another marketed EIA method.
| TABLE 3<br>Is-VZV IgG : Site #3 (manual) | | | TABLE 4<br>Is-VZV IgG : Site #3 (MAGO Plus) | | | | |
|----------------------------------------------------|-----------|----------|---------------------------------------------|-----------------------------------------------------|----------|-----------|------------------|
| | Positive | Negative | Equivocal | Positive | Negative | Equivocal | |
| Positive | 169 | 3 | 6 | 173 | 1 | 3 | |
| Other<br>EIA | Negative | 2 | 68 | 6 | 5 | 67 | 4 |
| EIA | Equivocal | 0 | 0 | 0 | 0 | 0 | 0 |
| | | | 95% <i>CI</i> ** | | | | 95% <i>CI</i> ** |
| Relative Sensitivity 169/172 = 98.3% 95.0-99.6 | | | | Relative Sensitivity 173/174 = 99.4% 96.8-100.0 | | | |
| Relative Specificity 68/70 = 97.1% 90.1-99.7 | | | | Relative Specificity 67/72 = 93.1% 84.5-97.7 | | | |
| Overall Agreement* 237/242 = 97.9% 95.2-99.3 | | | | Overall Agreement* 240/246 = 97.6% 94.8-99.1 | | | |
*Equivocal results were excluded from calculations
** Calculated by the Exact Method (10).
{2}------------------------------------------------
For site #3 (manual testing), the two samples that were positive by the ls-VZV IgG and negative by the other EIA were negative by a referee ElA method. For the three samples that were negative in the Is-VZV IgG Test Kit and positive by the other EIA one was negative, one was equivocal and one was possive in the referee method. For MAGO Plus testing the five samples that were positive in the Is-VZV IgG and negative by the other EIA were negative in the referee EIA method. The sample that was negative in the Is-VZV IgG Test Kit and positive by the other EIA was negative in the referee EIA method.
NOTE: Please be advised that 'relative' refers to the comparison of the assay's results to that of a similar assay. There was not an attempt to correlate the assay's results with disease presence or absence. No judgment can be made on the comparison assay's accuracy to predict disease.
#### B. Correlation of Manual and MAGO Plus Results
The Diamedix Is-VZV IgG Test System has been developed for use both manually and using the MAGO Plus Automated EIA Processor. To further demonstrate the equivalence of the manual and MAGO Plus procedures, the results of the 253 serum samples tested by both methods were plotted. A scattergram and regression line of the results obtained with 95% confidence intervals is shown in Figure 1 and demonstrates good correlation.
Image /page/2/Figure/4 description: The image is a scatter plot titled "FIGURE 1". The x-axis is labeled "MANUAL EU/ml", and the y-axis is labeled "MAGO Plus EU/ml". The scatter plot shows a positive correlation between the two variables. The equation of the line of best fit is given as Slope: 1.200, Intercept: 3.835, and Corr. Coeff. (r): 0.972.
### C. Linearity
Several strongly positive serum specimens as well as the in-house standard were dilutions were assayed in the Is-VZV IgG Test Kit both manually and using the MAGO Plus Automated Processor. Re values for the samples ranged from 0.972 to 0.999 The titration curve of the in-house standard, manually and by MAGO Plus, is shown in Figure 2. The results demonstrate a high degree of linearity throughout the reportable range of the assay.
Image /page/2/Figure/7 description: The image is a graph titled "FIGURE 2" that compares the EU/ml of Manual and MAGO Plus at different dilutions. The x-axis represents the dilution, ranging from 0.0 to 1.0, while the y-axis represents the EU/ml, ranging from 0.0 to 120.0. The graph shows that both Manual and MAGO Plus have a positive correlation between dilution and EU/ml. The equation for Manual is Y = 95.763 X + 4.961 with an R-squared value of 0.998, and the equation for MAGO Plus is Y = 90.449 X + 12.252 with an R-squared value of 0.984.
The linearity/dynamic range of the assay was determined to be 20-100 EU/ml
#### D. Semi-Quantitative Data
Serum pairs were obtained by preparing multiple serial 2-fold dilutions of several strongly positive sera. Ratios for dilutions representing a four-fold and two fold difference in antibody level were evaluated as a serum pair both manually and using the MAGO Plus. The overall mean ratio obtained for 4-fold dilutions was 3.13 (SD 0.35) and the overall mean ratio obtained for 2-fold dilutions was 1.77 (SD 0.15). Overall, it was estimated a ratio of 2.8-fold or greater (mean ratio minus 1 SD) increase in Is-VZV IgG EU/ml values corresponded to a four-fold incease in VZV IgG antibody levels. A ratio in the range of 1.8 to 2.8 was considered equivocal for significant increase determination.
{3}------------------------------------------------
### E. Cross Reactivity
Sera containing IgG antibodies to viruses potentially cross-reactive to VZV have been tested in the Is-VZV IgG Test Kit. Thirteen sera negative for antibodies to VZV in the Is-VZV IgG Test Kit as well as in another marketed test were positive for antibodes to one or more viruses. The data in the following table indicate that no cross-reactivity should be expected with the Is-VZV IgG Test Kit from these analytes.
| TABLE 5 | | | | | |
|------------------|---------|---------|-------------|-------------|---------|
| Analyte | VZV IgG | HSV IgG | Measles IgG | Rubella IgG | CMV IgG |
| # of Pos.Samples | 0 | 12 | 12 | 12 | 9 |
### F. Precision
Six serum samples as well as the Is-VZV IgG Test Kit Calibrator, Positive Control and Negative Control, were assayed, in triplicate in three separate runs for site #1 and in six separate runs for site #3. The precision studies were performed manually at the two outside testing sites (site #1 and site #3 (Diamedix Corp.) both manually and using the MAGO Plus Automated EIA processor. The results obtained are shown in Tables 6-10.
TABLE 6 : Site #1 Intra- and Interassay Precision
| SERUM | INTRA-ASSAY DAY 1 | | | INTRA-ASSAY DAY 2 | | | INTRA-ASSAY DAY 3 | | | INTERASSAY | | |
|-------|-------------------|------|------|-------------------|------|-------|-------------------|------|-------|------------|------|-------|
| | MEAN | SD | CV% | MEAN | SD | CV% | MEAN | SD | CV% | MEAN | SD | CV% |
| A | 1.5 | 0.10 | 6.67 | 1.5 | 0.25 | 16.67 | 1.5 | 0.17 | 11.33 | 1.5 | 0.16 | 10.67 |
| B | 3.9 | 0.25 | 6.41 | 4.1 | 0.23 | 5.61 | 4.1 | 0.26 | 6.34 | 4.0 | 0.23 | 5.75 |
| C | 16.9 | 1.45 | 8.58 | 16.8 | 1.56 | 9.29 | 17.4 | 0.83 | 4.77 | 17.0 | 1.18 | 6.94 |
| D | 49.5 | 3.43 | 6.93 | 49.1 | 3.44 | 7.01 | 48.0 | 3.20 | 6.67 | 48.9 | 2.99 | 6.11 |
| E | 81.9 | 5.58 | 6.81 | 81.2 | 5.14 | 6.33 | 84.3 | 1.84 | 2.18 | 82.4 | 4.16 | 5.05 |
| F | 102.4 | 2.67 | 2.61 | 101.6 | 2.68 | 2.64 | 101.9 | 2.32 | 2.28 | 102.0 | 2.24 | 2.20 |
| CAL | 93.4 | 2.76 | 2.96 | 93.0 | 3.10 | 3.33 | 92.4 | 3.55 | 3.84 | 93.0 | 2.76 | 2.97 |
| POS | 44.3 | 1.10 | 2.48 | 44.1 | 1.18 | 2.68 | 42.1 | 0.91 | 2.16 | 43.5 | 1.38 | 3.17 |
| NEG | 1.3 | 0.06 | 4.62 | 1.3 | 0.00 | 0.00 | 1.1 | 0.15 | 13.64 | 1.2 | 0.15 | 12.50 |
#### TABLE 7 : Site #2 Intra- and Interassay Precision
| SERUM | INTRA-ASSAY DAY 1 | | | INTRA-ASSAY DAY 2 | | | INTRA-ASSAY DAY 3 | | | INTERASSAY | | |
|-------|-------------------|-------|-------|-------------------|------|-------|-------------------|------|-------|------------|-------|-------|
| | MEAN | SD | CV% | MEAN | SD | CV% | MEAN | SD | CV% | MEAN | SD | CV% |
| A | 1.4 | 0.38 | 27.14 | 2.1 | 0.15 | 7.14 | 1.5 | 0.23 | 15.33 | 1.7 | 0.38 | 22.35 |
| B | 4.9 | 1.59 | 32.45 | 6.2 | 0.35 | 5.65 | 5.7 | 0.76 | 13.33 | 5.6 | 1.07 | 19.11 |
| C | 15.3 | 4.38 | 28.63 | 20.2 | 1.46 | 7.23 | 18.7 | 1.55 | 8.29 | 18.1 | 3.27 | 18.07 |
| D | 34.8 | 3.91 | 11.24 | 45.7 | 0.50 | 1.09 | 41.3 | 1.37 | 3.32 | 40.6 | 5.19 | 12.78 |
| E | 77.4 | 14.11 | 18.23 | 83.6 | 4.12 | 4.93 | 77.9 | 3.65 | 4.69 | 79.6 | 8.14 | 10.23 |
| F | 75.3 | 2.76 | 3.67 | 105.4 | 1.65 | 1.57 | 103.1 | 8.95 | 8.68 | 94.6 | 15.26 | 16.13 |
| CAL | 96.5 | 4.87 | 5.05 | 102.4 | 3.22 | 3.14 | 94.3 | 5.18 | 5.49 | 97.7 | 5.32 | 5.45 |
| POS | 45.8 | 2.41 | 5.26 | 55.2 | 3.35 | 6.07 | 51.0 | 2.75 | 5.39 | 50.7 | 4.78 | 9.43 |
| NEG | 1.6 | 0.03 | 18.75 | 1.8 | 0.51 | 28.33 | 2.0 | 0.76 | 38.00 | 1.82 | 0.52 | 28.89 |
TABLE 8 : Site #3 Intra- and Interassay Precision (Manual)
| SERUM | INTRA-ASSAY DAY 1 | | | INTRA-ASSAY DAY 2 | | | INTRA-ASSAY DAY 3 | | | INTERASSAY | | |
|-------|-------------------|------|-------|-------------------|------|-------|-------------------|------|------|------------|------|-------|
| | MEAN | SD | CV% | MEAN | SD | CV% | MEAN | SD | CV% | MEAN | SD | CV% |
| A | 1.7 | 0.08 | 4.90 | 1.9 | 0.10 | 5.26 | 1.8 | 0.10 | 5.56 | 1.8 | 0.14 | 7.78 |
| B | 4.4 | 0.45 | 10.17 | 4.7 | 0.53 | 11.26 | 4.3 | 0.35 | 8.06 | 4.4 | 0.37 | 8.41 |
| C | 18.2 | 0.81 | 4.43 | 17.7 | 1.03 | 5.79 | 17.1 | 0.58 | 3.37 | 17.5 | 0.89 | 5.09 |
| D | 46.7 | 1.64 | 3.51 | 46.3 | 1.47 | 3.19 | 45.3 | 1.15 | 2.54 | 45.5 | 2.63 | 5.78 |
| E | 71.7 | 2.78 | 3.88 | 71.6 | 4.12 | 5.76 | 68.3 | 1.70 | 2.49 | 70.3 | 3.09 | 4.40 |
| F | 99.3 | 5.12 | 5.16 | 99.9 | 4.03 | 4.03 | 95.2 | 6.53 | 6.86 | 97.9 | 5.38 | 5.50 |
| CAL | 97.8 | 7.15 | 7.31 | 98.6 | 7.35 | 7.46 | 98.3 | 5.26 | 5.36 | 97.1 | 6.25 | 6.44 |
| POS | 48.8 | 1.38 | 2.83 | 47.6 | 2.54 | 5.33 | 47.6 | 2.48 | 5.29 | 47.5 | 2.09 | 4.40 |
| NEG | 1.8 | 0.26 | 14.62 | 1.8 | 0.15 | 8.65 | 1.6 | 0.15 | 9.35 | 1.7 | 0.21 | 12.35 |
{4}------------------------------------------------
TABLE 9 : Site #3 Intra- and Interassay Precision (MAGO Plus)
| SERUM | INTRA-ASSAY DAY 1 | | | INTRA-ASSAY DAY 2 | | | INTRA-ASSAY DAY 3 | | | INTERASSAY | | |
|-------|-------------------|-------|-------|-------------------|-------|-------|-------------------|-------|-------|------------|-------|-------|
| | MEAN | SD | CV% | MEAN | SD | CV% | MEAN | SD | CV% | MEAN | SD | CV% |
| A | 2.7 | 1.07 | 40.23 | 2.4 | 0.71 | 29.95 | 3.0 | 0.29 | 9.48 | 2.7 | 0.77 | 28.52 |
| B | 4.4 | 0.77 | 17.58 | 4.6 | 0.92 | 19.95 | 5.4 | 0.50 | 9.14 | 4.8 | 0.84 | 17.50 |
| C | 19.9 | 1.97 | 9.92 | 21.1 | 1.11 | 5.27 | 21.4 | 1.31 | 6.13 | 20.8 | 1.56 | 7.50 |
| D | 51.3 | 1.75 | 3.41 | 52.2 | 3.60 | 6.90 | 58.1 | 4.02 | 6.91 | 53.9 | 4.39 | 8.14 |
| E | 91.2 | 10.07 | 11.04 | 96.3 | 10.26 | 10.65 | 98.5 | 15.09 | 15.32 | 95.3 | 11.73 | 12.31 |
| F | 108.0 | 6.47 | 5.99 | 117.1 | 6.48 | 5.53 | 117.7 | 8.03 | 6.82 | 114.3 | 8.03 | 7.03 |
| CAL | 112.8 | 10.45 | 9.26 | 119.0 | 8.80 | 7.39 | 128.5 | 13.17 | 10.25 | 120.1 | 12.23 | 10.18 |
| POS | 49.8 | 4.16 | 8.35 | 53.5 | 3.17 | 5.93 | 55.6 | 4.65 | 8.37 | 52.9 | 4.52 | 8.54 |
| NEG | 1.6 | 0.45 | 27.56 | 2.9 | 1.00 | 34.62 | 3.6 | 1.27 | 35.21 | 2.7 | 1.24 | 45.93 |
TABLE 10 : Inter-Site precision (manual)
| SERUM | Site #1<br>MEAN<br>EU/ml | Site #2<br>MEAN<br>EU/ml | Site #3<br>MEAN<br>EU/ml | INTER-SITE<br>MEAN<br>EU/ml | INTER-SITE<br>SD | INTER-SITE<br>CV% |
|-------|--------------------------|--------------------------|--------------------------|-----------------------------|------------------|-------------------|
| A | 1.5 | 1.7 | 1.8 | 1.7 | 0.15 | 8.82 |
| B | 4.0 | 5.6 | 4.4 | 4.7 | 0.83 | 17.66 |
| C | 17.0 | 18.1 | 17.5 | 17.5 | 0.55 | 3.14 |
| D | 48.9 | 40.6 | 45.0 | 45.0 | 4.17 | 9.27 |
| E | 82.4 | 79.6 | 70.3 | 77.4 | 6.33 | 8.18 |
| F | 102.0 | 94.6 | 97.9 | 98.2 | 3.71 | 3.78 |
| CAL | 93.0 | 97.7 | 97.1 | 95.9 | 2.56 | 2.67 |
| POS | 43.5 | 50.7 | 47.5 | 47.2 | 3.61 | 7.65 |
| NEG | 1.2 | 1.8 | 1.6 | 1.6 | 0.32 | 20.00 |
## Expected Values
The prevalence of VZV antibodies can vary depending on age, geographical location, socio-economic status, race and vaccine usage. The prevalence of VZV antibodies generally varies from about 15% positive in 2 year olds to about 95% in persons over 40 years of age. Sera from 100 healthy South Florida blood donors (52 female and 48 male) were evaluated in the Is-VZV IgG Test Kit. Of the 100 samples, 92 were found to be reactive (positive), 6 were found to be non-reactive (negative) and 2 sera were equivocal. Age distribution, geographic location and prevalence is provided in Table 11. Histograms demonstrating the distribution of EU/ml values are shown in Figures 3 and 4.
| | Number of donors | Prevalence |
|-------------------------------------------------|------------------|------------|
| Total Number | 100 | 92.0% |
| Geographic<br>location :<br>South Eastern<br>US | 100 | 92.0% |
| Age | | |
| 10-19 | 13 | 92.3% |
| 20-29 | 23 | 91.3% |
| 30-39 | 40 | 87.5.% |
| 40-49 | 13 | 100.0% |
| 50-59 | 5 | 100.0% |
| 60-69 | 6 | 100.0% |
TABLE 11
{5}------------------------------------------------
Image /page/5/Figure/0 description: The image contains two bar charts, labeled as Figure 3 and Figure 4, which display the frequency distribution of Is-VZV IgG levels in reactive (positive) and non-reactive (negative) populations. Figure 3 shows the distribution for the reactive population, with the highest frequency observed for levels greater than 100 EU/ml. Figure 4 shows the distribution for the non-reactive population, with the highest frequency observed for levels between 0-5 EU/ml.
{6}------------------------------------------------
Image /page/6/Picture/1 description: The image shows the seal of the Department of Health & Human Services (HHS) of the United States. The seal features a stylized eagle with three heads, representing the department's focus on health, human services, and science. The words "DEPARTMENT OF HEALTH & HUMAN SERVICES - USA" are arranged in a circular pattern around the eagle.
Food and Drug Administration 2098 Gaither Road Rockville MD 20850
SEP 2 8 1998
Lynne Stirling, Ph.D. Vice President, Regulatory Affairs Diamedix Corporation 2140 N. Miami Ave. Miami, FL 33127
K981867 Re: Trade Name: Is-VZV IgG Test System Regulatory Class: II Product Code: LFY Dated: July 23, 1998 Received: July 24, 1998
Dear Dr. Stirling:
We have reviewed your Section 510(k) notification of intent to market the device referenced above and we have determined the device is substantially equivalent (for the indications for use stated in the enclosure) to legally marketed predicate devices marketed in interstate commerce prior to May 28, 1976, the enactment date of the Medical Device Amendments, or to devices that have been reclassified in accordance with the provisions of the Federal Food, Drug, and Cosmetic Act (Act). You may, therefore, market the device, subject to the general controls provisions of the Act. The general controls provisions of the Act include requirements for annual registration, listing of devices, good manufacturing practice, labeling, and prohibitions against misbranding and adulteration.
If your device is classified (see above) into either class II (Special Controls) or class III (Premarket Approval), it may be subject to such additional controls. Existing major regulations affecting your device can be found in the Code of Federal Regulations, Title 21, Parts 800 to 895. A substantially equivalent determination assumes compliance with the Current Good Manufacturing Practice requirements, as set forth in the Quality System Regulation (QS) for Medical Devices: General regulation (21 CFR Part 820) and that, through periodic QS inspections, the Food and Drug Administration (FDA) will verify such assumptions. Failure to comply with the GMP regulation may result in regulatory action. In addition, FDA may publish further announcements concerning your device in the Federal Register. Please note: this response to your premarket notification submission does not affect any obligation you might have under sections 531 through 542 of the Act for devices under the Electronic Product Radiation Control provisions, or other Federal laws or regulations.
{7}------------------------------------------------
Page 2
Under the Clinical Laboratory Improvement Amendments of 1988 (CLIA-88), this device may require a CLIA complexity categorization. To determine if it does, you should contact the Centers for Disease Control and Prevention (CDC) at (770)488-7655.
This letter will allow you to begin marketing your device as described in your 510(k) premarket notification. The FDA finding of substantial equivalence of your device to a legally marketed predicate device results in a classification for your device and thus, permits your device to proceed to the market.
If you desire specific advice for your device on our labeling regulation (21 CFR Part 801 and additionally 809.10 for in vitro diagnostic devices), please contact the Office of Compliance at (301) 594-4588. Additionally, for questions on the promotion and advertising of your device, please contact the Office of Compliance at (301) 594-4639. Also, please note the regulation entitled, "Misbranding by reference to premarket notification" (21 CFR 807.97). Other general information on your responsibilities under the Act may be obtained from the Division of Small Manufacturers Assistance at its toll free number (800) 638-2041 or at (301) 443-6597 or at its internet address "http://www.fda.gov/cdrh/dsmamain.html"
Sincerely yours,
Steven Butman
Steven I. Gutman, M.D., M.B.A. Director Division of Clinical Laboratory Devices Office of Device Evaluation Center for Devices and Radiological Health
Enclosure
{8}------------------------------------------------
Appendix G. Rev. Indications for Use Statement
## INDICATIONS FOR USE STATEMENT
510(K) NUMBER : _ K 98 1867
## DEVICE NAME : Is-VZV IgG Test System
Indications for Use : For the qualitative and semi-quantitative detection of IgG antibodies to Varicella-Zoster Virus (VZV) in human serum by indirect immunoassay to determine a prior exposure to VZV and, when evaluating paired sera, to aid in the determination of acute or convalescent stage of VZV infection. These reagents can be used either manually or in conjunction with the MAGO® Plus Automated EIA Processor.
Woody Dubose
vision Sign Off Division of Clinical Laboratory Devices 510(k) Number_
000062
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Part 2 — Embeddings: the galaxy map 3 min
1. Search: exact and fuzzy
Type a phrase like "coronary artery calcification" into the search box. You get two kinds of results. Exact results match the literal phrase — prefix searches work ("coronary artery calcificati") but suffix searches do not. Fuzzy results match on the meaning and intent of your phrase rather than the exact words, and are sorted by relevance score. Hover over the Exact or Fuzzy badge on any row to see exactly why it matched.
Use the checkboxes above the results to narrow: SaMD keeps only software-only devices, AI / ML keeps only devices with AI.
Exact vs. fuzzy search: what's the difference?
Exact matches on the literal phrase (prefix search works, suffix does not). Fuzzy matches on the meaning and intent of the phrase rather than the exact words. Hover over the badge on any row to see why it matched.
You search "coronary artery calcification" and want only software devices with AI. What two filters do you apply?
Narrow by SaMD (software-only devices), then narrow by AI/ML (devices with AI).
2. The results table
Scroll right in the results table. The intended use is extracted for you — no need to open the PDF. The device story gives a high-level snapshot of what the device does and how it's used. The AI Performance sub-table shows each output name, acceptance criteria, observed values, and development/test dataset descriptions — the same format Innolitics uses for regulatory strategy outputs, and the fastest high-level fingerprint of an AI device. It is AI-generated but has been very reliable in practice.
Where do you find a device's intended use without opening the PDF?
Scroll right in the search results table. The intended use column is extracted for you; no need to dig into the 510(k) summary PDF.
What does the AI Performance sub-table show, and why is it useful?
Output name, acceptance criteria, observed values, development dataset description, and test dataset description. It's the same format we use for regulatory strategy output and Fast 510(k) input, and the fastest high-level fingerprint of an AI device. AI-generated but reliable in practice.
3. Judging fuzzy relevance
Fuzzy results trail off in relevance as you scroll. Use three signals to decide how far down to go: the fuzzy badge explanations, the intended use column, and whether your target output (e.g., Cobb angle) still appears in the AI Performance sub-table. Once it stops appearing, you're past the relevant zone. A top hit with a low score (~0.4) and a stretched explanation is a hint the closest predicates are far away — the project may be headed for De Novo. Note the fuzzy search is a pattern match: it doesn't handle negation ("not") well, and hardware devices can appear — filter by SaMD/AI ML to cut them.
How do you judge how far down fuzzy search results to go?
Use the relevancy signals: the fuzzy badge explanations, the intended use column, and whether the target output (e.g., Cobb angle) still appears in the AI Performance sub-table. Once it stops appearing, results are trailing off in relevancy.
4. Device detail page: chat and citations
Click a device name to open its detail page: device facts on the left, a chat window on the right. Ask something like "Describe the training data". The answer carries little citation bubbles — click one to jump to the highlighted passage in the source PDF, so you can verify every AI answer against the document. There's also a Download PDF button for sharing.
How do you verify an AI chat answer on the device detail page?
Click the citation bubbles to jump to the relevant highlight in the source document.
Reading rule for every project: how many summaries do you read in full?
At least the three most relevant 510(k) or De Novo summaries, in full. After that, use targeted chat questions to confirm your memory quickly. The tool supports this professional habit — it doesn't replace it.
5. Side-by-side comparison
Select multiple rows in the results table (aim for under ~10), then open the PDF Viewer tab. Ask one question — it goes to all selected devices in parallel, each with citations. This is the fastest way to compare and contrast devices: training data, PCCP scope, how they handled adding new scanners, and so on.
What does the side-by-side PDF viewer mode do?
Select multiple devices, open the PDF viewer tab, and ask one question (e.g., "Describe the training data"). It queries all selected devices simultaneously with citations, so you can compare and contrast quickly.
6. Collections
With rows selected, go to the Collections tab and create a labeled collection (e.g., "Cobb Angle Project"). Reload that selection any time — before a client call, pull up the collection and ask questions across all of its devices at once.
How do you save a set of selected devices for later use?
Select the rows, go to the Collections tab, and create a labeled collection (e.g., "Cobb Angle Project"). You can reload the selection anytime and carry it into the PDF viewer and other tabs that support selections.
7. Product codes and the regulations tree
Click a product code in the results to jump to it in the regulations tree — identification text, sibling product codes, and devices you can open in a PDF viewer on the right. Click a regulation number to see its identification, special controls, and related product codes. You can also search by product code or regulation number at the top of the tree. Always read the special controls if any exist for your device — it broadens your search and sharpens pre-kickoff research.
What can you do from the regulations tree view?
Browse product codes and regulation numbers, read the identification text and special controls, browse sibling product codes, open device PDFs on the right, and search by product code or regulation number at the top of the tree.
8. Chart view
Click Show Chart and segment by regulation number (or product code) to see which regulations dominate your result set. Clicking a regulation takes you into the regulations tree. Great for spotting that most matches are, say, hardware laparoscopic devices — a cue to go back and filter.
How do you see which regulations dominate a search result set?
Click "Show Chart" and segment by Regulation Number. Clicking a regulation takes you to the regulations tree.
9. The predicate graph
Open the Predicates tab for a family-tree view of predicate relationships. Click a node to trace its parents and children; selections from search carry over pre-selected. Commonly predicated devices are worth reading — a lot of people predicated them for a reason. The visual lineage is also handy on client calls, e.g. to show how a predicate family evolved and justify why your predicate still holds.
In the predicate graph, why are commonly predicated devices worth reading?
A lot of people predicated them for a reason. Clicking a node traces parents and children, and selections from search carry over pre-selected.
10. Embeddings: the galaxy map
The Embeddings tab plots every matching document in a 2-D "galaxy map" where semantically similar devices cluster together. Hover or click clusters to explore, and let AI label the clusters for you. Embeddings beat product codes for grouping: two devices can carry different product codes (LLZ vs. QIH) yet do the same thing — the embedding captures the meaning of the intended use and device story. This is also exactly how retrieval-augmented generation (RAG) works under the hood, and it makes a great visual on client calls.
Try it yourself
Head to the search page and work through a few of these AI/ML fuzzy searches to build intuition: perivascular fat on CT · aortic valve calcification opportunistic screening on noncontrast CT · breast cancer prediction on digital pathology slides · autism detection · gestational age prediction · a hearing aid that can also detect a pulse · foundation model based analysis of ECG · large language models · penetration test. Watch how the relevance scores, intended use, and AI Performance tables tell you when results stop being meaningful.