Peer Review History

Original SubmissionApril 3, 2020
Decision Letter - Jeffrey Shaman, Editor

PONE-D-20-09603

Work-related Covid-19 transmission

PLOS ONE

Dear Dr. Kales,

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.

Please respond on a point-by-point basis to the reviewer comments and revise the manuscript accordingly.

We would appreciate receiving your revised manuscript by Jun 11 2020 11:59PM. When you are ready to submit your revision, log on to https://www.editorialmanager.com/pone/ and select the 'Submissions Needing Revision' folder to locate your manuscript file.

If you would like to make changes to your financial disclosure, please include your updated statement in your cover letter.

To enhance the reproducibility of your results, we recommend that if applicable you deposit your laboratory protocols in protocols.io, where a protocol can be assigned its own identifier (DOI) such that it can be cited independently in the future. For instructions see: http://journals.plos.org/plosone/s/submission-guidelines#loc-laboratory-protocols

Please include the following items when submitting your revised manuscript:

  • A rebuttal letter that responds to each point raised by the academic editor and reviewer(s). This letter should be uploaded as separate file and labeled 'Response to Reviewers'.
  • A marked-up copy of your manuscript that highlights changes made to the original version. This file should be uploaded as separate file and labeled 'Revised Manuscript with Track Changes'.
  • An unmarked version of your revised paper without tracked changes. This file should be uploaded as separate file and labeled 'Manuscript'.

Please note while forming your response, if your article is accepted, you may have the opportunity to make the peer review history publicly available. The record will include editor decision letters (with reviews) and your responses to reviewer comments. If eligible, we will contact you to opt in or out.

We look forward to receiving your revised manuscript.

Kind regards,

Jeffrey Shaman

Academic Editor

PLOS ONE

Journal Requirements:

When submitting your revision, we need you to address these additional requirements.

1. Please ensure that your manuscript meets PLOS ONE's style requirements, including those for file naming. The PLOS ONE style templates can be found at

https://journals.plos.org/plosone/s/file?id=wjVg/PLOSOne_formatting_sample_main_body.pdf and

https://journals.plos.org/plosone/s/file?id=ba62/PLOSOne_formatting_sample_title_authors_affiliations.pdf

2. Please consider modifying your title to ensure that it is specific, descriptive, concise, and comprehensible to readers outside the field (for example by specifying the nature of the study, and the names of the countries analysed ). When making changes please ensure that you amend the title on the online submission form (via Edit Submission) and the title in the manuscript so that they are identical.

3. In your Methods section, please detail the data sources used.

4. PLOS requires an ORCID iD for the corresponding author in Editorial Manager on papers submitted after December 6th, 2016. Please ensure that you have an ORCID iD and that it is validated in Editorial Manager. To do this, go to ‘Update my Information’ (in the upper left-hand corner of the main menu), and click on the Fetch/Validate link next to the ORCID field. This will take you to the ORCID site and allow you to create a new iD or authenticate a pre-existing iD in Editorial Manager. Please see the following video for instructions on linking an ORCID iD to your Editorial Manager account: https://www.youtube.com/watch?v=_xcclfuvtxQ

5. Please include a caption for figures 1 and 2.

6. Please include captions for your Supporting Information files at the end of your manuscript, and update any in-text citations to match accordingly. Please see our Supporting Information guidelines for more information: http://journals.plos.org/plosone/s/supporting-information

[Note: HTML markup is below. Please do not edit.]

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

**********

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

Reviewer #1: I Don't Know

Reviewer #2: N/A

**********

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: No

Reviewer #2: Yes

**********

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

**********

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 this manuscript, the authors calculated the case number for each occupation, and illustrated the temporal distribution of all possible work-related cases and healthcare worker (HCW) cases by extracting confirmed COVID-19 cases from governmental investigation reports in six countries/areas. The results indicate the importance of work-related transmission in the local COVID-19 outbreak. They further found that the proportion of HCWs among locally transmitted cases was smaller than non-HCWs in the included countries/areas, emphasizing the importance of implementing effective infection control in the non-healthcare workplaces to protect the workers in this pandemic. This study provides a new insight in understanding the epidemiology of work-related transmission of COVID-19 and implement evidence-based prevention and protection strategies in workplaces. One concern from me is if there should be some difference among these countries and what should be the reasons?

Reviewer #2: The objective of this study was to describe the occupations among early COVID-19 cases arising from local transmission in five Asian countries for cases where occupational was thought to contribute to disease transmission, based on governmental reports. The investigators look at two time period, first week after introduction and the next month. Infections among healthcare workers appeared in the second period, and there were suggestions of some other changes in the distribution but interpretation is limited by the small sample size. It is important to understand what occupations put individuals at risk of COVID-19 to inform the need for intervention at the individual level and the society level.

Specific comments:

1. It would be helpful to know more about the data, including extraction of occupation and the judgement of occupationally-related disease transmission. For example, how frequently was occupation information missing? What types of occupations were identified that were judged not related to disease transmission? How was occupation recorded in the governmental reports, and did this vary among countries? What is the confidence in the role of occupation when an infection source could not be identified?

2. The sensitivity analysis with Japan is not well justified. Why was it thought that variation data recording practices among prefectures in Japan was greater among the four other coutnries? What was the evidence of this? The sensitivity results suggest that adding Japan wasn't a big impact on the results.

3. The results section text is very repetitive.

4. Figure 2 is difficult to read in black and white, or for people with color vision problems. Suggest using different line textures or thicknesses to enhance readability.

**********

6. 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

Reviewer #2: No

[NOTE: If reviewer comments were submitted as an attachment file, they will be attached to this email and accessible via the submission site. Please log into your account, locate the manuscript record, and check for the action link "View Attachments". If this link does not appear, there are no attachment files to be viewed.]

While revising your submission, please upload your figure files to the Preflight Analysis and Conversion Engine (PACE) digital diagnostic tool, https://pacev2.apexcovantage.com/. PACE helps ensure that figures meet PLOS requirements. To use PACE, you must first register as a user. Registration is free. Then, login and navigate to the UPLOAD tab, where you will find detailed instructions on how to use the tool. If you encounter any issues or have any questions when using PACE, please email us at figures@plos.org. Please note that Supporting Information files do not need this step.

Revision 1

Journal Requirements:

1. Please ensure that your manuscript meets PLOS ONE's style requirements, including those for file naming. The PLOS ONE style templates can be found at

https://journals.plos.org/plosone/s/file?id=wjVg/PLOSOne_formatting_sample_main_body.pdf and

https://journals.plos.org/plosone/s/file?id=ba62/PLOSOne_formatting_sample_title_authors_affiliations.pdf

Response: Thank you. We have revised the format/file names according to PLOS ONE’s requirements throughout the paper.

2. Please consider modifying your title to ensure that it is specific, descriptive, concise, and comprehensible to readers outside the field (for example by specifying the nature of the study, and the names of the countries analysed ). When making changes please ensure that you amend the title on the online submission form (via Edit Submission) and the title in the manuscript so that they are identical.

Response: Thank you. The paper title has been modified to “Work-related COVID-19 transmission in six Asian countries/areas: a follow-up study”, and the change has been made throughout the submission.

3. In your Methods section, please detail the data sources used.

Response: Thank you. The data sources have been added as references, as follows.

We extracted and included all locally transmitted COVID-19 confirmed cases from the publicized government investigation reports from six Asian countries/areas, including Hong Kong [15], Japan [16], Singapore [17], Taiwan [18], Thailand [19], and Vietnam [20].

15. Centre for Health Protection [Internet]. Media Room: Press Releases; c2020 [cited 2020 April 28]. Available from: https://www.chp.gov.hk/en/media/116/index.html

16. Ministry of Health, Labour and Welfare [Internet]. 報道発表資料; c2020 [cited 2020 April 28]. Available from: https://www.mhlw.go.jp/stf/houdou/index.html

17. Singapore Ministry of Health [Internet]. Past Updates on COVID-19 Local Situation; c2020 [cited 2020 April 28]. Available from: https://www.moh.gov.sg/covid-19/past-updates

18. Taiwan Centers for Disease Control [Internet]; c2020 [cited 2020 April 28]. Available from: https://www.cdc.gov.tw/En

19. Department of Disease Control [Internet]; Corona Virus Disease (COVID-19): Press Release; c2020 [cited 2020 April 28]. Available from: https://ddc.moph.go.th/viralpneumonia/eng/news.php

20. Ministry of Health [Internet]; c2020 [cited 2020 April 28]. Available from: https://ncov.moh.gov.vn

4. PLOS requires an ORCID iD for the corresponding author in Editorial Manager on papers submitted after December 6th, 2016. Please ensure that you have an ORCID iD and that it is validated in Editorial Manager. To do this, go to ‘Update my Information’ (in the upper left-hand corner of the main menu), and click on the Fetch/Validate link next to the ORCID field. This will take you to the ORCID site and allow you to create a new iD or authenticate a pre-existing iD in Editorial Manager. Please see the following video for instructions on linking an ORCID iD to your Editorial Manager account: https://www.youtube.com/watch?v=_xcclfuvtxQ

Response: Thank you. Dr Kales’ (the corresponding author) account has been linked to his ORCID iD.

5. Please include a caption for figures 1 and 2.

Response: Thank you. The captions of Fig 1 and Fig 2 have been embedded in the manuscript body.

6. Please include captions for your Supporting Information files at the end of your manuscript, and update any in-text citations to match accordingly. Please see our Supporting Information guidelines for more information: http://journals.plos.org/plosone/s/supporting-information

Response: Thank you. The caption of S1 Table has been included at the end of the manuscript (after References). The in-text citation has also been updated to match accordingly.

Reviewer #1: In this manuscript, the authors calculated the case number for each occupation, and illustrated the temporal distribution of all possible work-related cases and healthcare worker (HCW) cases by extracting confirmed COVID-19 cases from governmental investigation reports in six countries/areas. The results indicate the importance of work-related transmission in the local COVID-19 outbreak. They further found that the proportion of HCWs among locally transmitted cases was smaller than non-HCWs in the included countries/areas, emphasizing the importance of implementing effective infection control in the non-healthcare workplaces to protect the workers in this pandemic. This study provides a new insight in understanding the epidemiology of work-related transmission of COVID-19 and implement evidence-based prevention and protection strategies in workplaces. One concern from me is if there should be some difference among these countries and what should be the reasons?

Response: Thank you. Different countries do have different disease investigation and reporting policies, probably due to various political systems, historical factors, religious reasons, and so on. In the revised discussion, we addressed the limitation that there were discrepancies in reporting and investigation across the countries/areas. This is also the reason we excluded Japan as a sensitivity analysis, because unlike other countries/areas that have central reporting systems, Japan reports cases from each prefecture separately.

Reviewer #2: The objective of this study was to describe the occupations among early COVID-19 cases arising from local transmission in five Asian countries for cases where occupational was thought to contribute to disease transmission, based on governmental reports. The investigators look at two time period, first week after introduction and the next month. Infections among healthcare workers appeared in the second period, and there were suggestions of some other changes in the distribution but interpretation is limited by the small sample size. It is important to understand what occupations put individuals at risk of COVID-19 to inform the need for intervention at the individual level and the society level.

Specific comments:

1. It would be helpful to know more about the data, including extraction of occupation and the judgment of occupationally-related disease transmission. For example, how frequently was occupation information missing? What types of occupations were identified that were judged not related to disease transmission? How was occupation recorded in the governmental reports, and did this vary among countries? What is the confidence in the role of occupation when an infection source could not be identified?

Response: Thank you for your comments. Please find the point-by-point responses below.

1) We have added more detailed descriptions of the government reports, as follows.

The investigation reports of the six countries/areas mostly included case information such as age, sex, and brief contact/medical history. An example is: “The new case was a 35 year-old female health care worker, and had close contacts with the Xth confirmed case [19].” There were also sections indicating infection clusters: “Four of the confirmed cases (Cases W, X, Y and Z) are linked to the XXX construction site [17].” Occupational history was not always available. In most cases, if the contact history was obvious such as family cluster, the report would likely lack an occupational description. Based on the available information, each case report was reviewed by two occupational physicians and categorized for work-relatedness.

2) Most cases judged not related to work were because of obvious non-occupational contact history or a lack of occupational history. Therefore, we did not determine particular types of occupations that were not related to disease transmission.

3) Different countries do have different disease investigation and reporting policies. Occupational history was not generally reported for each case. However, for the reports with available and adequate occupation information, we were able to determine the possible work-relatedness. We addressed this issue in the discussion as a limitation that cases without reported occupational history could potentially lead to underestimation in the analysis.

4) We were more confident in determining the work-relatedness if a case had close contact with a confirmed case due to work, or Category 1, such as a registered nurse having a history of directly caring for a patient who is an index confirmed case. As to Category 2, unknown transmission source; no apparent contact history but likely to be infected in the working environment, such as an airport taxi driver without clear contact history to any confirmed case, we had less confidence in work-relatedness but judged such cases to be probable (or more likely than not) work-related.

2. The sensitivity analysis with Japan is not well justified. Why was it thought that variation data recording practices among prefectures in Japan was greater among the four other countries? What was the evidence of this? The sensitivity results suggest that adding Japan wasn't a big impact on the results.

Response: Thank you for your comments. We have revised the following sentences and added references accordingly as follows.

Unlike other countries/areas that have central reporting systems providing cases’ occupation and other contact history in a standardized form, Japan’s reporting system is prefecture-based, where each prefecture reports separately, without consistent occupational coding. For example, some prefectures reported a case as a taxi driver; while some prefectures only reported a driver, without specifying the type of vehicle he/she drove [16,22,23]. Differences in reporting mechanisms and case information across prefectures could potentially bias the results.

16. Ministry of Health, Labour and Welfare [Internet]. 報道発表資料; c2020 [cited 2020 April 28]. Available from: https://www.mhlw.go.jp/stf/houdou/index.html

22. Ministry of Health, Labour and Welfare [Internet]. 新型コロナウイルス感染症患者の発生について(第 2 報); c2020 [cited 2020 April 28]. Available from: https://www.mhlw.go.jp/content/10906000/000598149.pdf?fbclid=IwAR0SZCxLB4VruarnnbNNcsfyGG-Bb96y_KXFBIX3UR4t7B_BzhlbIA4_6Gk

23. Ministry of Health, Labour and Welfare [Internet]. 新型コロナウイルス感染症患者の発生について(県内8・9・10例目); c2020 [cited 2020 April 28]. Available from: https://www.mhlw.go.jp/content/10906000/000609268.pdf?fbclid=IwAR1bImIVvBWmrftmd0X0cCrmmg6HJdnD2F8UsXm3c9j-jtAEO3Hs8y0nYGA

Therefore, the exclusion of Japan is because of the concerns of potential misclassification. The most substantial impact after excluding Japan was the proportion of non-HCWs among work-related cases raised from 78% to 93% (shown in the revised Results).

3. The results section text is very repetitive.

Response: Thank you for your comments. We have streamlined the text of Results by incorporating sensitivity analysis results into the main results, as follow.

HCW comprised 22% of the possible work-related cases. In the sensitivity analysis excluding Japan, the proportion of HCWs decreased to 7%. Moreover, we found the occurrence of COVID-19 transmission among the HCW was relatively late compared to the non-HCW population. Fig 2A and Fig 2B showed a two-week lag of the first HCW case after the local COVID-19 outbreak (median lag: 15 days, IQR 13-20 days). The median time lag from the report of the first possible work-related case to the first HCW case was 13.5 days (IQR: 12.3-14.5 days) among the study population. In further sensitivity analysis excluding Japan, the median lags were 14 days (range: 10-32 days) and 13 days (range: 10-14 days), respectively.

4. Figure 2 is difficult to read in black and white, or for people with color vision problems. Suggest using different line textures or thicknesses to enhance readability.

Response: Thank you for your comments. We have revised the figures.

Attachments
Attachment
Submitted filename: Response to Reviewers.docx
Decision Letter - Jeffrey Shaman, Editor

Work-related COVID-19 transmission in six Asian countries/areas: a follow-up study

PONE-D-20-09603R1

Dear Dr. Kales,

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

Within one week, you will receive an e-mail containing information on the amendments required prior to publication. When all required modifications have been addressed, you will receive a formal acceptance letter and your manuscript will proceed to our production department and be scheduled for publication.

Shortly after the formal acceptance letter is sent, an invoice for payment will follow. To ensure an efficient production and billing process, please log into Editorial Manager at https://www.editorialmanager.com/pone/, click the "Update My Information" link at the top of the page, and update your user information. If you have any billing related questions, please contact our Author Billing department directly at authorbilling@plos.org.

If your institution or institutions have a press office, please notify them about your upcoming paper to enable them to help maximize its impact. If they will be preparing press materials for this manuscript, you must inform our press team as soon as possible and no later than 48 hours after receiving the formal acceptance. Your manuscript will remain under strict press embargo until 2 pm Eastern Time on the date of publication. For more information, please contact onepress@plos.org.

With kind regards,

Jeffrey Shaman

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

Reviewer #2: All comments have been addressed

**********

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: (No Response)

Reviewer #2: Yes

**********

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

Reviewer #1: (No Response)

Reviewer #2: 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: (No Response)

Reviewer #2: Yes

**********

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: (No Response)

Reviewer #2: 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)

Reviewer #2: The authors have addressed the comments from this reviewer, and the manuscript is improved. The figures look better.

**********

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

Reviewer #2: No

Formally Accepted
Acceptance Letter - Jeffrey Shaman, Editor

PONE-D-20-09603R1

Work-related COVID-19 transmission in six Asian countries/areas: a follow-up study

Dear Dr. Kales:

I am pleased to inform you that your manuscript has been deemed suitable for publication in PLOS ONE. Congratulations! Your manuscript is now with our production department.

If your institution or institutions have a press office, please notify them about your upcoming paper at this point, to enable them to help maximize its impact. If they will be preparing press materials for this manuscript, please inform our press team within the next 48 hours. Your manuscript will remain under strict press embargo until 2 pm Eastern Time on the date of publication. For more information please contact onepress@plos.org.

For any other questions or concerns, please email plosone@plos.org.

Thank you for submitting your work to PLOS ONE.

With kind regards,

PLOS ONE Editorial Office Staff

on behalf of

Prof. Jeffrey Shaman

Academic Editor

PLOS ONE

Open letter on the publication of peer review reports

PLOS recognizes the benefits of transparency in the peer review process. Therefore, we enable the publication of all of the content of peer review and author responses alongside final, published articles. Reviewers remain anonymous, unless they choose to reveal their names.

We encourage other journals to join us in this initiative. We hope that our action inspires the community, including researchers, research funders, and research institutions, to recognize the benefits of published peer review reports for all parts of the research system.

Learn more at ASAPbio .