PONE-D-21-03832

Investigation and public health response to a COVID-19 outbreak in a rural resort community — Blaine County, Idaho, 2020

PLOS ONE

Dear Dr. Dunne,

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Shinya Tsuzuki, MD, MSc

Academic Editor

PLOS ONE

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Additional Editor Comments:

Both reviewers gave insightful suggestions then please revise your manuscript accordingly.

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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: No

Reviewer #2: Yes

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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: No

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: Summary

This report summarizes an outbreak investigation of COVID-19 in a rural county in Idaho with a popular resort community early in the course of pandemic-related events in the US. This report highlights some of the challenges faced early in the pandemic response, when testing was limited and public health action delayed due to the lack of widespread availability of rapid tests. This report is well written, and represents a thorough investigation, including case interview/medical record review, contact tracing, sequencing, etc. This report does not add much insight into COVID-19 epidemiology; however, it does provide insight into the issues challenging the response early in the pandemic and in rural areas.

Major Issues

This report is very well written and covers many important aspects of a COVID-19 outbreak investigation despite the limitations of being early in the pandemic when less was known about risk factors, asymptomatic spread, etc. I have very few suggestions to improve it, other than the few provided below.

The report uses only descriptive statistics to describe the outbreak. However, there is a place for analytic epidemiology in this report. The authors should consider conducting multivariable logistic regression to examine risk factors for hospitalization and report ORs with 95% CIs instead of just frequency of age ranges for those hospitalized.

Minor Issues

Suggest reporting frequency/percent of individuals reporting one and multiple symptoms (e.g., 1, 2-4, 5+) or something similar. Were there any set of symptoms that most commonly occurred together?

Reviewer #2: The authors have reported on an investigation of COVID-19 in a rural resort community. The report is comprehensive of many aspects of the outbreak and response. However, it lacks the focus that would make it a useful scientific paper. For example, it is noted that the outbreak occurred after a ski event at the local ski resort. However, there is no real assessment of how that event contributed to spread across the county. The rural nature of the county is emphasized, as is the resort nature of the community. These raise separate, important issues with regard to transmission risk and control, and neither is fully addressed. The abstract describes the occurrence of 452 cases during March 13-April 10. However, the epicurve (figure 1) identifies more than 60-70 cases with onset of symptoms before March 13. The epi-curve and the descriptions of the outbreak are difficult to reconcile. I think that it would be useful to focus on the impact of the ski resort in the initiation of the outbreak. It would also be useful to highlight the interactions of the control measures on the epi-curve (fig. 1). If the epi-curve could be labeled with all of the key time line events, (ski festival, school closure, resort closure, county isolation order, state isolation order, travel restriction) it would provide a clear visual guide to the progression of the outbreak. This would be a better way to relate control measures to case incidence than is achieved in figure 3. The use of cumulative frequency data make it difficult to track the rate of new case onsets. It would be an even bigger bonus if the cases identified by sequence cluster could also be indicated on the epi-curve. I recognize that may not be feasible.

It seems that approximately 1/3 of the population of the county at any given time may be made up by visitors from out of state. It would be useful to try to estimate the rate of illness in this ephemeral group, or at least try to better estimate the impact of visitors on transmission dynamics. It is critical for similar resort communities to try to plan for potential disease introductions from tourists, and to have plans for surveillance and control of spread related to these temporary residents. It may be true that such cases are not typically counted as cases in the temporary community, but that does not diminish the importance of being able to track and account for them.

There are descriptions of definitions of close contacts on p.4, and changes in the definition. There does not seem to be any use of this data in the paper. If it is not being used for analytical purposes, is it needed in the methods? Similarly, there is substantial description of census blocks in the methods. The results do not present more than a cursory analysis of the census block data, that could be omitted. How do the census blocks relate to housing for guests of the resort?

The introductions and discussions are very broad. Given the vast literature that is being published on the pandemic, a narrower focus on the impact of the ski resort on the community would enhance the interest and usefulness of this paper.

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Reviewer #1: No

Reviewer #2: No

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Investigation and public health response to a COVID-19 outbreak in a rural resort community — Blaine County, Idaho, 2020

PONE-D-21-03832R1

Dear Dr. Dunne,

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,

Shinya Tsuzuki, MD, MSc

Academic Editor

PLOS ONE

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

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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

Reviewer #2: Yes

**********

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

Reviewer #1: Yes

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: Yes

Reviewer #2: 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

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: Thank you for addressing my comments and the other reviewer's comments. This paper is much stronger now.

Reviewer #2: The authors have addressed reviewer's comments. The figure with the control measures imposed on the epi-curve is very nice.

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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

Reviewer #2: No