PONE-D-21-03214

Accurate Point-of-Care Serology Tests for COVID-19

PLOS ONE

Dear Dr. Schuler IV,

Thank you for submitting your manuscript to PLOS ONE. After careful consideration, we feel that it has merit but does not fully meet PLOS ONE’s publication criteria as it currently stands. Therefore, we invite you to submit a revised version of the manuscript that addresses the points raised during the review process.

One of the reviewers questioned whether to include data on the Autobio assay since the assay was terminated half way through the study, however I encourage you to include this information never the less. Kindly include an ethics statement in the manuscript and please revise all references to ensure they match PLoS One requirements (i.e. reference 8 currently only says "FDA")

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Benedikt Ley

Academic Editor

PLOS ONE

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[The authors acknowledge the generosity of Healgen, Access Bio, and Autobio companies who donated the LFA for this study.]

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Please remove any funding-related text from the manuscript and let us know how you would like to update your Funding Statement. Currently, your Funding Statement reads as follows:

 [The funders had no role in study design, data collection and interpretation, manuscript

drafting, manuscript editing, or the decision to submit the work for publication. This

work was supported by The University of Michigan (Institutional Funding, COVID-19

Innovation Grant, https://www.research.umich.edu/covid-19/covid-19-fundingopportunities),

the National Institutes of Health (UL1TR002240), and through related

sponsored projects from Healgen Scientific (healgen.com) and Access Bio Inc

(accessbiodiagnostics.net).]

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Reviewers' comments:

Reviewer's Responses to Questions

Comments to the Author

1. Is the manuscript technically sound, and do the data support the conclusions?

The manuscript must describe a technically sound piece of scientific research with data that supports the conclusions. Experiments must have been conducted rigorously, with appropriate controls, replication, and sample sizes. The conclusions must be drawn appropriately based on the data presented.

Reviewer #1: Yes

Reviewer #2: Yes

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2. Has the statistical analysis been performed appropriately and rigorously?

Reviewer #1: Yes

Reviewer #2: Yes

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3. Have the authors made all data underlying the findings in their manuscript fully available?

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Reviewer #1: No

Reviewer #2: Yes

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Reviewer #1: Yes

Reviewer #2: Yes

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5. Review Comments to the Author

Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters)

Reviewer #1: In general, the manuscript is well written and will be of interest to policy makers and HCPs responding to COVID-19. I’m not entirely convinced the Autobio information should be included since this LFA was discontinued early in the study, but I will leave that up to the editor and submitting authors. Please see below for issues that should be addressed before publishing.

Methods

When did this study occur? Please provide details on enrollment period.

Why did you stop using the Autobio assay? I understand that the EUA approval was revoked but I’m assuming clinical decisions weren’t being made based on POC assays. Why not continue testing your original research question and add to the body of literature about the performance of the Autobio assay?

Results

Please include positive and negative predictive values in results (can also go in supplemental docs)

Line 149 – is it worth including Autobio results as a supplementary? Did the poor performance align with what other studies were finding? Alternatively, should any detail about the Autobio be included in this study given early termination? It might make the entire paper cleaner if all Autobio is removed or sent to appendix .

Did age or occupation (HCW vs general pop) have any impact on POC performance or rates? Please mention.

Discussion

Please describe your interpretation of specificity of these assays. FPs are equally concerning as FNs, possibly even more so, given that a FP might result in a change in behavior, a false sense of security, and an increase in risk taking.

Please add a limitation that you don’t know how the POC will perform in immune compromised individuals.

Can you provide any details or estimates on costs differences between approaches? POC fingerstick will be much cheaper, but capturing the magnitude here will be of value for readers.

Line 263 – is it correct to describe all three LFAs showing good concordance? Above you mention that only CareStart and Healgen were tested against both finger stick and serum. There are also differences in sample sizes, with only 149 tested using Autobio.

You touch on it briefly (line 282), but in my opinion the strongest application of POC testing regarding vaccines would be a “screen before vaccine” approach in areas with limited access to vaccines – where individuals without antibodies are prioritized over those with previous exposure. This is by no means fool proof, but if herd immunity is the ultimate goal, this approach would expedite that process by prioritizing POC – cases, and moving POC +s to the back of the vaccine que. However, such an approach would only be appropriate when vaccinating general population, where high risk/vulnerable populations should receive the vaccine regardless of POC status. When monitoring vaccine adverse events this assay may have some utility, but it should not replace quantitative serological assays that can better describe immune response.

I somewhat disagree with line 284 – LFAs are unable to quantify concentration of antibodies, or if detected antibody confers protective immunity, instead it’s a marker of previous exposure. I think you would need to test these POCs in vaccinated populations before making this statement.

Reviewer #2: Dear Authors,

I am wondering why you'd need to evaluate the LFA that have been FDA approved? However, if your aim is to evaluate these using finger-stick samples for recent/past infection, then this should be highlighted. Not what's written on line 92 of your manuscript.

Furthermore, I have the following comments/questions to your manuscript:

1. Why not use a quantitative test as reference CLIA test rather than a qualitative albeit CLIA immunoassay?

2. In all your results, you combined PCR (-) and no PCR. Since you do get positive response to antibody test, perhaps it's better to differentiate them. No PCR could mean that this person has Covid-19 already, whereas PCR (-) was undetectable viral particle meaning, there should not be any antibody response. This brings it to my next question,

3. How do you ensure that the results you obtained are not due to false positive? The positive result could be due to other coronavirus infection or other factors such as prior pregnancy or autoimmune response?

4. For the no PCR/PCR(-) column, those who were positive for antibody test, I wonder how long has it been since PCR? Since I can't see it from your results.

5. For PCR (+) are all subjects have been infected only once with Sars-CoV-2?

6. Has there been any validation for Roche Elecys anti Sars-CoV-2 against a reference standard? I am just wondering why the authors choose this immunoassay instead of others?

7. I don't understand the difference between Healgen PCR, Healgen serum versus Healgen serum.

8. It's interesting to see if you can have the IgG and IgM put together instead of IgM(-), whether when both are present, they either amplify or subdued the expression of one another.

Thank you.

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Reviewer #1: Yes: Michael von Fricken

Reviewer #2: No

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Accurate Point-of-Care Serology Tests for COVID-19

PONE-D-21-03214R1

Dear Dr. Schuler IV,

We’re pleased to inform you that your manuscript has been judged scientifically suitable for publication and will be formally accepted for publication once it meets all outstanding technical requirements.

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Kind regards,

Benedikt Ley

Academic Editor

PLOS ONE

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