An Optimal Nucleic Acid Testing Strategy for COVID-19 during the Spring Festival Travel Rush in Mainland China: A Modelling Study

Round 1

Reviewer 1 Report

Introduction:

Line 33: Please rewrite as, ‘according to a website FlightAware……….’

Line 41: Replace the word ‘Then’ with ‘after which’ in a continuing sentence corresponding to the prior sentence.

Line 49: Can the source of website be replaced with a reference number and the weblink be instead placed in the reference section of bibliography.

Methods:

Table 1: I would recommend including the full text reference in addition to the numbered references in table 1. It will be easier for the reader to refer to the paper instead of having to go back and forth for the reference especially when presented in a tabular format.

Line 105: Please replace the number 6 with the word ‘six’ at eh beginning of the sentence. The authors mention that they use six scenarios for model simulation but mention only three. Please rectify.

Results:

Please include the abbreviation NAT in subtitle 3.4 since it is used widely under that sub heading

Line 177: Could you please provide a reference for the policy

Discussion:

Line 193: Same suggestion as line 49. Please put the source of website accessed along with a date under references and use a numbered reference for the in-text citation.

Line 219: Please correct the grammar and use the correct ‘tense’ for the sentence.

Line 228: Please correct the grammar at the end of the sentence.

Please mention strengths of the study in addition to study limitations.

Author Response

Please see the attachment.

Author Response File: Author Response.docx

Reviewer 2 Report

It is important that the calculations are reviewed/repeated with the correct incubation period (see notes) 

Language:  The manuscript needs close examination and proof-reading by an experienced natural speaker of English.  There are many errors that indicate either inexperience with English or that a machine translation has been used.  One set of problems is with verb-tenses.

Line 14 for example reads:

“… This study aimed to explore whether mainland China will face an epidemic rebound

during the Spring Festival holiday, when millions of Chinese people travelled across the

country.” 

The future tense “will face” contradicts the past (preterite) tense “travelled”.

 

Line 32  “had” should read “have”

Line 70  “…parameters on to the natural history…”     Not sure what this means

Line 70  “…were referred to the published studies…”  Does this mean “…taken from…”?

Line 72  “…we set that each individual …”    Not clear what “set” means here.

Line 76  “…the incidence was varied from 1 to 100 …”  Need to decide why “was” is included here.

Line 75-76 – Two uses of the word “was” suggest that these activities have already taken place. Is this correct?   If so, it is not clear how and what the activities have already been completed.  The paper appears to be proposing monitoring starting with the holiday travel on January 28. 

Line 78-79….  This sentence also refers to past activities.   If this is also the same “past” activities, as for lines 75-76, then perhaps the authors can clarify for the reader what is in the past and what will be in the future.

[There are many other syntax and grammatical errors]

 

Layout:

Lines 58-62: The objectives are important.  Suggest listing and numbering these four(?) objectives for clarity and retrospective review to verify that each was addressed

 

Table 1.  “ Incubation period 3 days”. AND the range (2-5 days).  This is clearly incorrect.  The mean incubation period is about 6 days (J.A. Backer, D. Klinkenberg & J. Wallinga, Eurosurveillance 25, 10–15; 2020).  The reference used by the authors was subsequently CORRECTED by the authors of the source paper quoted.  PLEASE SEE:  https://europepmc.org/article/pmc/pmc7413015#free-full-text

This figure for the incubation period appears to have been used in the calculations at the core of the paper, so at the very least, the calculations should be reviewed using the correct I.P.

 

Table 1.    Can the figure for the relative risk (2) be explained further?  Where is it calculated?

 

Line 88-89. I wonder if the assumption is valid (that  that people who were slightly symptomatic would not travel by train during this period.).  I suspect people will "hope" their symptoms are innocent, and will still travel to see family.  This group could be a major cause of additional cases.

 

 

 

 

 

Fig S1.    This is a SEIR model modified for Covid-19.  

Problems include definitions of  I = infectious “OR” As = asymptomatic. 

By using “OR”, this excludes the Infectious-asymptomatic cases!  BOTH symptomatic and asymptomatic people are potentially infectious to varying degrees.

So, a better division would be symptomatic-infectious and asymptomatic-infectious

 

Also in Fig S1, the RED text we are told indicates “infectiousness”, yet the “Q” is shown in black.    The reason the people are in quarantine is that they MAY be infectious- we simply don’t know but we keep them in quarentine for at least one incubation period.  The “Q” should be red.    

 

Fig S2   Suggest removing repeated phrase “effective reproduction number”

 

General comments

Modelling exercises such as this can be useful and provide insight into some of the more obscure mechanisms of epidemic spread. Of course, models are only as valid as the assumptions they are based upon. I am pleased to see that the authors have listed and considered the validity of some of the assumptions in the last paragraph.

Author Response

Please see the attachment.

Author Response File: Author Response.docx

Reviewer 3 Report

in this work, the authors explore whether mainland China will face an epidemic rebound during the Spring holidays. This is an important problem, in view that many Chisease people use to travel around the country. The study is based on a microsimulation model to simulate the SARS-CoV-2 transmission among railway travelers, and some strategies to contain the propagation of the virus are proposed based on those results. As a result, the authors conclude that pre-travel testing could reduce the number of active infections.

COMMENTS

In my opinion, the paper lacks sufficiently novelty and scientific sound to guarantee its publication in the IJERPH. My decision is based on the following comments:

1. The paper lacks a methodological novelty to assure its publication in this journal. Indeed, the authors base their work on the use of a microsimulation model previously reported in [7]. In view of this fact, the present work is a straightforward application of a previously reported simulation tool. No novelty is found in that practice.
2. The model considers the presence of various subpopulations: susceptible, exposed, pre-symptomatic, infectious and recovered. The use of such model has not been justified by the authors. However, after a careful review of the model, it seems that the classification of the populations is not entirely justified by the evidence on the propagation of COVID-19. Indeed, to be able to spread the disease, a person can be symptomatic or asymptomatic!
3. The control options are relatively limited.
4. The conclusion (that pre-travel testing could reduce the number of active infections) is entirely expected. No need to carry out a simulation study to that end.

In view of these comments, I recommend the paper for REJECTION.

 

IJERPH

Author Response

Please see the attachment.

Author Response File: Author Response.docx

Round 2

Reviewer 3 Report

The authors have improved the manuscript. However, the work is a routine application of standard methods already available in the literature. The conclusions aren't particularly groundbreaking, As a routine and straightforward work, it is acceptable.