PONE-D-20-20858

Antibodies against SARS-CoV-2 among health care workers in a country with low burden of COVID-19

PLOS ONE

Dear Dr. Psichogiou,

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.

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Ronald Dijkman, PhD

Academic Editor

PLOS ONE

Additional Editor Comments:

Based on the available literature and deficits of certain early phase commercial serological assays, and reviewer comments, I would recommend that the authors would confirm their finding with an additional serological assay, in order for the revised version of their manuscript to be considered.

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"Gilead Hellas (https://www.gilead.com/utility/global-operations/europe/greece/greek) has funded the study with a grant bearing an approval code number GR-515-03.2020  after the approval by the Gilead Hellas Grants Committee at the colloquy of March 23d, 2020. Recipient of the grant was AH. The funders had no role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript."

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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: No

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

Reviewer #1: No

Reviewer #2: No

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

The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception (please refer to the Data Availability Statement in the manuscript PDF file). The data should be provided as part of the manuscript or its supporting information, or deposited to a public repository. For example, in addition to summary statistics, the data points behind means, medians and variance measures should be available. If there are restrictions on publicly sharing data—e.g. participant privacy or use of data from a third party—those must be specified.

Reviewer #1: Yes

Reviewer #2: Yes

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4. Is the manuscript presented in an intelligible fashion and written in standard English?

PLOS ONE does not copyedit accepted manuscripts, so the language in submitted articles must be clear, correct, and unambiguous. Any typographical or grammatical errors should be corrected at revision, so please note any specific errors here.

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: The manuscript by Psichogiou describes a study on health care workers in Greece. A low level of immunity was found which mirrors the low rate on infection in Greece. The low prevalence of people with antibodies to SARS-CoV-2 cannot draw conclusions on risk factors, which is unfortunate. Still the low prevalence is worthwhile sharing with the scientific community.

Suggestions for improvement;

- line 111, please add the viral protein that is used as target in the GeneBody COVID-19 antibody detection test.

- line 140-141 and line 158 – 159: It is mentioned that seroprevalence is 10, 4 or 20 times higher than the general population. However, these numbers are probably not significant as the CI of the hospital tests is so wide. Please provide P-values, and mention whether there is a significant difference (or not).

Reviewer #2: Pichogiou et al. perform a serological testing for COVID-19 among health care workers in Greece, a country with low burden of COVID-19. First, the major issue is lack of detailed description for the commercial kit from Genebody Inc they used for antibody testing. what is the catalogue Number? Is it a quantitative or qualitative gold immunochromatography assay? It will be great if the authors use alternative assay to confirm the positive samples. Otherwise, it is hard to know the seropositive individuals identified from this assay were really positive or false positive. Also, the author mentioned that "capillary blood" was used for testing, instead of venous blood. From our practical experience, capillary blood might cause false positivity.

Secondly, some key details of socio-demographic characteristics of HCWs in two hospitals were missing. For examples, how many individuals in hospital-1 were front line HCW (FL-HCW)? How many of them directly exposed to COVID-19 patients without proper PPE? How many seropositive HCWs used PPE? Only identifying the seroprevalence among HCWs has limited implication for preparedness of a second wave of COVID-19.

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Reviewer #1: No

Reviewer #2: No

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Antibodies against SARS-CoV-2 among health care workers in a country with low burden of COVID-19

PONE-D-20-20858R1

Dear Dr. Psichogiou,

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.

Within one week, you’ll receive an e-mail detailing the required amendments. When these have been addressed, you’ll receive a formal acceptance letter and your manuscript will be scheduled for publication.

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Kind regards,

Ronald Dijkman, PhD

Academic Editor

PLOS ONE

Additional Editor Comments (optional):

Reviewers' comments:

Reviewer's Responses to Questions

Comments to the Author

1. If the authors have adequately addressed your comments raised in a previous round of review and you feel that this manuscript is now acceptable for publication, you may indicate that here to bypass the “Comments to the Author” section, enter your conflict of interest statement in the “Confidential to Editor” section, and submit your "Accept" recommendation.

Reviewer #1: All comments have been addressed

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2. 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

**********

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

Reviewer #1: Yes

**********

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

The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception (please refer to the Data Availability Statement in the manuscript PDF file). The data should be provided as part of the manuscript or its supporting information, or deposited to a public repository. For example, in addition to summary statistics, the data points behind means, medians and variance measures should be available. If there are restrictions on publicly sharing data—e.g. participant privacy or use of data from a third party—those must be specified.

Reviewer #1: Yes

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5. Is the manuscript presented in an intelligible fashion and written in standard English?

PLOS ONE does not copyedit accepted manuscripts, so the language in submitted articles must be clear, correct, and unambiguous. Any typographical or grammatical errors should be corrected at revision, so please note any specific errors here.

Reviewer #1: Yes

**********

6. 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: (No Response)

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7. PLOS authors have the option to publish the peer review history of their article (what does this mean?). If published, this will include your full peer review and any attached files.

If you choose “no”, your identity will remain anonymous but your review may still be made public.

Do you want your identity to be public for this peer review? For information about this choice, including consent withdrawal, please see our Privacy Policy.

Reviewer #1: No