-->PONE-D-25-40092-->-->Mental health of healthcare workers in England during the first three years of the COVID-19 pandemic: the NHS CHECK study cohort-->-->PLOS One

Dear Dr. Lamb,

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PLOS One

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2. Thank you for stating the following financial disclosure: [NHS CHECK received funding from the Medical Research Council (MR/V034405/1), UCL/Wellcome (ISSF3/H17RCO/C3), Rosetrees (M952), Economic and Social Research Council (ES/V009931/1),].

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4. Thank you for stating the following in the Competing Interests section: [I have read the journal's policy and the authors of this manuscript have the following competing interests:

SW has received speaker fees from Swiss Re for two webinars on the epidemiological impact of the COVID 19 pandemic on mental health.

NG reports a potential COI with NHSEI,  during the conduct of the study. He is the managing director of March on Stress Ltd which has provided training for a number of NHS organisations.

Other authors report no competing interests.].

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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: Yes

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: Yes

Reviewer #2: No

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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 study's goals were to identify the staff members most at risk of negative mental health outcomes and investigate differences in mental health over a three-year period across all staff types. My observations are given below:

(1) The study title is okay.

(2) The abstract needs minor revision. Although the abstract reads densely and places little emphasis on theoretical foundation or novelty, it is clear, thorough, and methodologically sound. The findings are succinctly summarized, but the implications—which should highlight particular practical approaches and possible advances in occupational mental health research—could be more critically stated.

(3) The background also needs minor revision. It offers a thorough and organized summary of the body of research on the effects of COVID-19 on healthcare workers' mental health. It persuasively argues for the importance of the NHS CHECK study and draws attention to research gaps, especially the disregard for non-clinical staff. It could, however, more effectively synthesize findings to create a stronger conceptual justification because it is a little descriptive. The explanation of earlier discrepancies (e.g. G. between HCW and overall population distress) requires more precise incorporation into the objectives of the study. To improve focus and cut down on repetition, some parts could be simplified. Please include cross-cultural research on the mental health outcomes of the COVID-19 pandemic and add the following research in the background:

Tiwari, G. K., Singh, A. K., Parihar, P., Pandey, R., Sharma, D. N., & Rai, P. K. (2023). Understanding the perceived psychological distress and health outcomes of children during COVID-19 pandemic. Educational and Developmental Psychologist, 40(1), 103–114. https://doi.org/10.1080/20590776.2021.1899749

Tiwari, G. K., Tiwari, R. P., Pandey, R., Ray, B., Dwivedi, A., Sharma, D. N., Singh, P., Tiwari, A. K., & Singh, A. K. (2024). Perceived Life Outcomes of Indian Children During the Early Phase of the COVID-19 Lockdown: The Protective Roles of Joint and Nuclear Families. Journal of Research and Health, 14(1), 43–54. https://doi.org/10.32598/JRH.14.1.1992.4

(4) The methods section also needs improvements. Although the study uses a strong longitudinal cohort design with suitable follow-up intervals, there are a number of methodological issues. It's possible that selection bias was introduced during participant recruitment through internal communication channels, reducing representativeness. Over time, attrition bias and response accuracy become issues when self-reported online data is used. Despite the use of validated measures, data uniformity was diminished by varying survey lengths. Although the imputation and weighting techniques are suitable, they are not sufficiently supported. Response rates, how to handle missing data, and steps to guarantee validity and reliability across time-points all require more clarification.

(5) The results section also needs revision. The results section demonstrates thorough handling of extensive longitudinal data and is methodologically transparent and detailed. However, readability is hampered by too much tabular data, and certain tables (e.g. G. are not effectively incorporated into the story (Table 2). Significant attrition rates across time-points cast doubt on the representativeness and possible bias of longitudinal results. Weighted regression and VIF are suitable statistical controls, but interpretations are unclear regarding their applicability. There is little inferential commentary that connects findings to theoretical or contextual implications, and the description of outcomes (CMDs, PTSD, burnout) is primarily descriptive.

(6) The discussion section also needs revision. It is thorough, organized, and skillfully incorporates the results with previously published works. It provides little theoretical interpretation, though, and is more descriptive than analytical. A few associations (e.g. G. ethnicity, gender, and so forth) are reported without sufficient investigation of the underlying mechanisms. A more thorough examination of the causal pathways, implications of the intervention, and contextual interpretation of the results would enhance this section. The limitations are discussed in a defensive manner, even though strengths and limitations are duly acknowledged. The impact and coherence of the discussion would be improved by placing more focus on the real-world applications and policy translation. Please include the following research from other cultural contexts to interpret the study findings:

Tiwari, G. K., Rai, P. K., Dwivedi, A., Ray, B., Pandey, A., & Pandey, R. (2023). A Narrative Thematic Analysis of the perceived psychological distress and health outcomes in Indian adults during the early phase of the COVID-19 pandemic. Psychology: The Journal of the Hellenic Psychological Society, 28(1), 213–229. https://doi.org/10.12681/psy_hps.28062

(7) The references are okay. Please correct it by following the journal’s guidelines. The tables and figures should be prepared following standard guidelines.

Reviewer #2: Comments for authors

1. Conceptual novelty is limited

While the sample size is impressive, the theoretical contribution is limited. The introduction could benefit from integrating: occupational stress models, moral injury frameworks, and burnout theory.

The paper is largely descriptive and confirms patterns already widely reported in COVID-19 mental health research. The discussion should better clarify what new knowledge this cohort provides beyond existing studies.

2. Cross-sectional analysis of a longitudinal cohort

Although the study is designed as longitudinal, the current analysis treats the data cross-sectionally at each timepoint.

This reduces the potential contribution of the cohort. Include at least one longitudinal model if possible (e.g., mixed effects or growth curve) to justify the cohort design.

3. Response bias and representativeness

The baseline response rate is only 16%, which raises serious concerns regarding:

• self-selection bias

• overrepresentation of distressed participants

Although weighting was applied, the manuscript should discuss this limitation more explicitly.

4. Attrition across timepoints

Participant numbers decrease substantially:

Baseline: 22,092

6 months: 10,514

12 months: 11,998 (includes replenishment cohort)

32 months: 6,991

Attrition could bias the results if individuals with worse mental health dropped out.

The authors should provide:

• attrition analysis

• comparison of responders vs non-responders.

5. Interpretation of CMD prevalence

The authors report that ~50% of staff met GHQ-12 caseness, which is extremely high.

However:

GHQ-12 “caseness” indicates psychological distress, not clinical disorder. The manuscript occasionally implies clinical diagnosis. Clarify throughout that this represents probable distress rather than confirmed mental disorder.

6. Moral injury measurement limitations

The study dichotomizes the Moral Injury Events Scale (MIES) using endorsement of a single item. More nuanced analysis (e.g., subscales) would strengthen the findings.

Also:

Typographical errors: Example: “writeen consent” instead of written consent.

Line 421 contains: “Error! Not a valid bookmark self-reference”. This must be corrected before publication.

Data availability statement: The manuscript states that data are available upon request, which does not fully comply with PLOS ONE data sharing policy. Authors should deposit data in a repository or justify restrictions.

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Reviewer #1: Yes: Gyanesh Kumar Tiwari

Reviewer #2: No

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Mental health of healthcare workers in England during the first three years of the COVID-19 pandemic: the NHS CHECK study cohort

PONE-D-25-40092R1

Dear Dr. Lamb,

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,

Giuseppe Marano

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: Dear authors. I carefully went over the manuscript once more. I am pleased with the authors' efforts to revise the work. I believe that every query posed in the initial review has been addressed by the writers. The manuscript is now more comprehensive and easier to read. Its technical fit has improved in the interim. The manuscript as it stands, in my opinion, can advance knowledge. No further changes are required.

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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: Yes: Gyanesh Kumar Tiwari

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