PONE-D-22-03741Does 2x2 airplane passenger contact tracing for infectious respiratory pathogens work? A systematic review of the evidence.PLOS ONE

Dear Dr. Kirk,

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.

==============================Both reviewers agree that your manuscript would benefit from changes. Please address all of their suggestions.==============================

Please submit your revised manuscript by Jun 04 2022 11:59PM. If you will need more time than this to complete your revisions, please reply to this message or contact the journal office at plosone@plos.org. When you're 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.

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). You should upload this letter as a separate file labeled 'Response to Reviewers'.
• A marked-up copy of your manuscript that highlights changes made to the original version. You should upload this as a separate file labeled 'Revised Manuscript with Track Changes'.
• An unmarked version of your revised paper without tracked changes. You should upload this as a separate file labeled 'Manuscript'.

If you would like to make changes to your financial disclosure, please include your updated statement in your cover letter. Guidelines for resubmitting your figure files are available below the reviewer comments at the end of this letter.

If applicable, we recommend that you deposit your laboratory protocols in protocols.io to enhance the reproducibility of your results. Protocols.io assigns your protocol its own identifier (DOI) so that it can be cited independently in the future. For instructions see: https://journals.plos.org/plosone/s/submission-guidelines#loc-laboratory-protocols. Additionally, PLOS ONE offers an option for publishing peer-reviewed Lab Protocol articles, which describe protocols hosted on protocols.io. Read more information on sharing protocols at https://plos.org/protocols?utm_medium=editorial-email&utm_source=authorletters&utm_campaign=protocols.

We look forward to receiving your revised manuscript.

Kind regards,

Joël Mossong

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. In your Data Availability statement, you have not specified where the minimal data set underlying the results described in your manuscript can be found. PLOS defines a study's minimal data set as the underlying data used to reach the conclusions drawn in the manuscript and any additional data required to replicate the reported study findings in their entirety. All PLOS journals require that the minimal data set be made fully available. For more information about our data policy, please see http://journals.plos.org/plosone/s/data-availability.

Upon re-submitting your revised manuscript, please upload your study’s minimal underlying data set as either Supporting Information files or to a stable, public repository and include the relevant URLs, DOIs, or accession numbers within your revised cover letter. For a list of acceptable repositories, please see http://journals.plos.org/plosone/s/data-availability#loc-recommended-repositories. Any potentially identifying patient information must be fully anonymized.

Important: If there are ethical or legal restrictions to sharing your data publicly, please explain these restrictions in detail. Please see our guidelines for more information on what we consider unacceptable restrictions to publicly sharing data: http://journals.plos.org/plosone/s/data-availability#loc-unacceptable-data-access-restrictions. Note that it is not acceptable for the authors to be the sole named individuals responsible for ensuring data access.

We will update your Data Availability statement to reflect the information you provide in your cover letter.

3. We note that you have stated that you will provide repository information for your data at acceptance. Should your manuscript be accepted for publication, we will hold it until you provide the relevant accession numbers or DOIs necessary to access your data. If you wish to make changes to your Data Availability statement, please describe these changes in your cover letter and we will update your Data Availability statement to reflect the information you provide.

4. Thank you for stating the following in the Acknowledgments Section of your manuscript:

“ACR is funded by the Master of Philosophy (Applied Epidemiology) Scholarship at Australian National University. MDK is supported by a National Health and Medical Research Council fellowship (APP1145997).”

We note that you have provided additional information within the Acknowledgements Section that is not currently declared in your Funding Statement. Please note that funding information should not appear in the Acknowledgments section or other areas of your manuscript. We will only publish funding information present in the Funding Statement section of the online submission form.

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:

“ACR is funded by the Master of Philosophy (Applied Epidemiology) Scholarship at Australian National University. MDK is supported by a National Health and Medical Research Council fellowship (APP1145997).

The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.”

Please include your amended statements within your cover letter; we will change the online submission form on your behalf.

5. Please ensure that you refer to Figure 2, 3, 4, 5 and 6 in your text as, if accepted, production will need this reference to link the reader to the figure.

Please review your reference list to ensure that it is complete and correct. If you have cited papers that have been retracted, please include the rationale for doing so in the manuscript text, or remove these references and replace them with relevant current references. Any changes to the reference list should be mentioned in the rebuttal letter that accompanies your revised manuscript. If you need to cite a retracted article, indicate the article’s retracted status in the References list and also include a citation and full reference for the retraction notice.

[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: Yes

Reviewer #2: I Don't Know

********** 

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

********** 

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: I read it with great interest, but I have raised several concerns.

#1. In my common sense, it is known that 2*2 contact tracing in flight was accepted as a well-established theory after publising the landmark previoust study in NEJM 2003. I hope to have a more specific discussion on this.

Olsen SJ, Chang HL, Cheung TY, Tang AF, Fisk TL, Ooi SP, Kuo HW, Jiang DD, Chen KT, Lando J, Hsu KH, Chen TJ, Dowell SF. Transmission of the severe acute respiratory syndrome on aircraft. N Engl J Med. 2003 Dec 18;349(25):2416-22. doi: 10.1056/NEJMoa031349. PMID: 14681507.

#2. In abstract method, please describe the assessing tool of evidence level for Plos One readers.

#3.Since the author did not analyze meta-statistics for 2*2 contact tracing, the main results may be over-interpreted.

Reviewer #2: REVIEW - PONE-D-22-03741

Title: Does 2x2 airplane passenger contact tracing for infectious respiratory pathogens work? A systematic review of the evidence.

PLOS ONE

1. Summary of the research and your overall impression

General comment:

This study addresses the relevant question of which literature is available to date of in-flight transmissions of respiratory infections (in the context of limited data available for SARS-CoV-2) for informed public health policies and recommendations for passenger contact tracing.

The method (Systematic Literature Review) is well chosen to answer the research question. The review workflow was well conducted from the registration of the review on PROSPERO 2020 CRD42020191261 in the beginning, the use of the respective PRISMA guidelines/ checklist, the utilised databases and other sources (incl. relevant international organisations/ authorities, search for relevant grey literature, snowballing) as well as the review process itself (e.g. screening, definition of inclusion/ exclusion criteria, data extraction). I do not have the expertise to consider the statistics in detail, but the methods of analysis given seem appropriate (AR, pooled AR/meta-analysis).

The authors are aware of the limitations of their study and have taken these into account in their conclusions.

Recommended course of action:

The identified evidence can be useful for future decision making and recommendations. It would therefore be helpful to publish the article. However, this paper could benefit from some clarifications in the results and discussion section (see part 2).

Suggested improvements:

Publish with minor revision

2. Discussion of specific areas for improvement

Major Issues

Results: Study characteristics: page 8, line 144-147 and figure 1:

The authors should clarify the following section to avoid confusion. The numbers in the text of the manuscript and the flowchart do not correspond. Figure 1 shows “studies included in qualitative synthesis n=102”. Line 144 refers to 103 enclosed articles. If applicable, add “number finally included studies in meta-analysis” to the text to link flowchart and results (line 185 and table 1).

Results: page 13: line 210-213:

The authors should check and revise (if applicable) the numbers in this passage. The authors refer to 32 investigations where transmission outside the 2x2 zone was reported, but the sum of the investigations listed per pathogen does not add up to 32.

Results: page 14, Assessment of the evidence and bias, line 227-233:

The authors should clarify the following section to avoid confusion. Here, reference is made to studies that demonstrate in-flight transmission or provide evidence of in-flight transmission, but with different denominators [in line 227-228: n=165 (sum of 46, 71 and 48) and in line 231: n=72]. The difference between the denominators is not clear to the reader.

"We assessed that 46 studies had a high level of evidence ... demonstrating in-flight transmission." (see line 227) and "Of the 72 studies that provided evidence of in-flight transmission, ..." (see line 231).

My understanding of the data presented is that the first denominator refers to the "number of unique investigations in the review", i.e. all 165 flight investigations (see line 146). The second denominator refers to investigations providing evidence of in-flight transmission of respiratory illness (see line 178-179).

Discussion: page 16: line 264-266:

The authors should check and clarify the following sentence: “Just under half of the investigations that reported on proximity showed transmission occurring beyond the 2x2 area.”

From my understanding of the data presented, there are 46 investigations that reported on proximity, of which 32 investigations reported transmission outside the 2x2 zone (see results page 13). That would result in almost 70% (32/46) and would be more than half of the investigations.

Perhaps the authors confused investigations and secondary cases in this summary of results, see page 13, line 208: “…, 48.7% (94/193) of reported secondary cases occurred outside of the 2x2 seating area around the index case.”

Minor Issues

Introduction: page 4, line 71-73:

Please add reference for this statement: “The evidence for in-flight transmission can also be confounded by interactions elsewhere during the journey, for example in the airport terminal or in transit to or from the airport.”

Introduction: page 4, line 73-74:

In my opinion the following sentence is not part of the introduction, rather part of the results or discussion. If desired, move the statement to the respective section of the paper.

“It is not always clear within the papers reviewed what provision has been made to handle such confounders during an outbreak investigation.”

Methods: page 7, line 130-133:

The authors may indicate how many reviewers assessed the risk of bias (see PRISMA Checklist Item 11). Likewise, two reviewers as for the data screening and extraction process?

“Articles were assessed on the strength of evidence of each investigation and categorised as low, medium, or high evidence, based on factors relevant to contact tracing, such as methodology,

timeliness and outcomes.”

Methods: page 7, line 136-141:

Please add reference for the following paragraph: “Tuberculosis studies were also complicated by the extended latency period and corresponding delays in investigations. Tuberculosis investigations commonly involved multiple flights, rather than being conducted on an individual flight basis as is typical of more acute pathogens such as SARS-CoV-2, SARS-CoV, Middle East Respiratory Syndrome (MERS) or H1N1, which have pandemic potential and rapid transmission.”

Results: page 8-9, line 164-166:

Please add the reference for the publication mentioned. This is presumably reference #118.

“We included an unpublished Australian report detailing several investigations 165 into flight-associated transmission of SARS-CoV-2.”

Results: page 11, table 1:

Please add the denominator in column 1 "Number of articles in the meta-analysis" (n=44) and column 5 "Number of individual studies in the review" (n=165) to better link the manuscript text and the data reported in the table.

Results: page 14, table 2:

Please add the denominator (n=72) in the caption to better link the manuscript text and table.

Discussion: page 15, line 237-240:

The following finding is a repetition, please see result section line 208-209. Consider rephrasing this finding without repeating the numbers.

“We found that 48.7% (94/193) of all respiratory pathogen transmission events, where proximity was reported, occurred outside of the standard arrangement that public health uses to contact trace a 2x2 seating area around an infected passenger”

Discussion: page 16, line 277-278:

I am not a native English speaker, but the authors should consider rephrasing the following sentence regarding the clause ".... to one or fewer persons ..." to make the meaning clearer: “In addition, it is likely that the many instances infectious cases transmitted to one or fewer persons were not published.” The wording seems misleading, persons count as a whole, and less than one person is "no" person. Perhaps the authors mean "one or only a few persons", but then I think it would be useful to quantify the "few".

Ref. 14: The format of the title seems wrong: “Probability and Estimated Risk of SARS-CoV-2 Transmission in the Air Travel System: A Systemic Review and Meta-Analysis” doi: 10.1101/2021.04.08.21255171; doi: 10.1016/j.tm

********** 

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.]

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 PLOS at figures@plos.org. Please note that Supporting Information files do not need this step.

Attachments

Attachment

Submitted filename: PONE-D-22-03741_review_JS.pdf

PONE-D-22-03741R1Does 2x2 airplane passenger contact tracing for infectious respiratory pathogens work? A systematic review of the evidence.PLOS ONE

Dear Dr. Kirk,

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 reviewer still spotted some minor work to be done. Please address this before resubmitting.==============================

Please submit your revised manuscript by Jan 12 2023 11:59PM. If you will need more time than this to complete your revisions, please reply to this message or contact the journal office at plosone@plos.org. When you're 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.

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). You should upload this letter as a separate file labeled 'Response to Reviewers'.
• A marked-up copy of your manuscript that highlights changes made to the original version. You should upload this as a separate file labeled 'Revised Manuscript with Track Changes'.
• An unmarked version of your revised paper without tracked changes. You should upload this as a separate file labeled 'Manuscript'.

If you would like to make changes to your financial disclosure, please include your updated statement in your cover letter. Guidelines for resubmitting your figure files are available below the reviewer comments at the end of this letter.

If applicable, we recommend that you deposit your laboratory protocols in protocols.io to enhance the reproducibility of your results. Protocols.io assigns your protocol its own identifier (DOI) so that it can be cited independently in the future. For instructions see: https://journals.plos.org/plosone/s/submission-guidelines#loc-laboratory-protocols. Additionally, PLOS ONE offers an option for publishing peer-reviewed Lab Protocol articles, which describe protocols hosted on protocols.io. Read more information on sharing protocols at https://plos.org/protocols?utm_medium=editorial-email&utm_source=authorletters&utm_campaign=protocols.

We look forward to receiving your revised manuscript.

Kind regards,

Joël Mossong, PhD

Academic Editor

PLOS ONE

Journal Requirements:

Please review your reference list to ensure that it is complete and correct. If you have cited papers that have been retracted, please include the rationale for doing so in the manuscript text, or remove these references and replace them with relevant current references. Any changes to the reference list should be mentioned in the rebuttal letter that accompanies your revised manuscript. If you need to cite a retracted article, indicate the article’s retracted status in the References list and also include a citation and full reference for the retraction notice.

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

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 #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 #2: Yes

**********

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

Reviewer #2: I Don't Know

**********

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 #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 #2: No

**********

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 #2: Thank you for the thorough revision.

Nevertheless, I have 2 minimal comments:

1) Maybe I don't have the right version of the revised manuscript, but the reference to my comment #6 is still missing (please see p. 7, line 137-142).

2) Line288-289: "In addition, it is likely that the many instances where infectious cases transmitted to one no other passengers were not published." If necessary, the author could check this sentence again, as it is still not entirely clear. Perhaps an "or" is missing.

Thank you for your efforts.

**********

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 #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.]

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 PLOS at figures@plos.org. Please note that Supporting Information files do not need this step.

Does 2x2 airplane passenger contact tracing for infectious respiratory pathogens work? A systematic review of the evidence.

PONE-D-22-03741R2

Dear Dr. Kirk,

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.

An invoice for payment will follow shortly after the formal acceptance. To ensure an efficient process, please log into Editorial Manager at http://www.editorialmanager.com/pone/, click the 'Update My Information' link at the top of the page, and double check that your user information is up-to-date. 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 help maximize its impact. If they’ll be preparing press materials, please inform our press team as soon as possible -- 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.

Kind regards,

Joel Mossong, PhD

Academic Editor

PLOS ONE

Additional Editor Comments (optional):

Reviewers' comments: