Beyond coverage: Can vaccination reduce child mortality despite structural inequality? A global ecological analysis of routine childhood immunization (2010–2023)

Valeria Rios Montoya; Arlet Yelisse Suarez Alarcon; Shamira Perez Castillo; Trilce Zamudio Raez; Antonio Marty Quispe

doi:10.1371/journal.pone.0340756

Peer Review History

Original SubmissionDecember 27, 2025
2 Mar 2026 Decision Letter - Vanya Rangelova, Editor PONE-D-25-68661Beyond coverage: can vaccination reduce child mortality despite structural inequality? A global ecological analysis of routine childhood immunization (2010–2023)PLOS One Dear Dr. Quispe, 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 submit your revised manuscript by Apr 16 2026 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 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, Vanya Rangelova, M.D., Ph.D. 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. Thank you for stating the following in the Competing Interests section: [The authors have declared that no competing interests exist]. We note that one or more of the authors are employed by a commercial company: Universidad Senor de Sipan. 1. Please provide an amended Funding Statement declaring this commercial affiliation, as well as a statement regarding the Role of Funders in your study. If the funding organization did not play a role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript and only provided financial support in the form of authors' salaries and/or research materials, please review your statements relating to the author contributions, and ensure you have specifically and accurately indicated the role(s) that these authors had in your study. You can update author roles in the Author Contributions section of the online submission form. Please also include the following statement within your amended Funding Statement. “The funder provided support in the form of salaries for authors [insert relevant initials], but did not have any additional role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript. The specific roles of these authors are articulated in the ‘author contributions’ section.” If your commercial affiliation did play a role in your study, please state and explain this role within your updated Funding Statement. 2. Please also provide an updated Competing Interests Statement declaring this commercial affiliation along with any other relevant declarations relating to employment, consultancy, patents, products in development, or marketed products, etc. Within your Competing Interests Statement, please confirm that this commercial affiliation does not alter your adherence to all PLOS ONE policies on sharing data and materials by including the following statement: "This does not alter our adherence to PLOS ONE policies on sharing data and materials.” (as detailed online in our guide for authors http://journals.plos.org/plosone/s/competing-interests) . If this adherence statement is not accurate and there are restrictions on sharing of data and/or materials, please state these. Please note that we cannot proceed with consideration of your article until this information has been declared. Please include both an updated Funding Statement and Competing Interests Statement in your cover letter. We will change the online submission form on your behalf. 3. Please update your captions for your Supporting Information files at the end of your manuscript. Please renumber the captions for your Supporting Information files and update any in-text citations to ensure they follow a sequential order so it matches accordingly. Please see our Supporting Information guidelines for more information: http://journals.plos.org/plosone/s/supporting-information. If the reviewer comments include a recommendation to cite specific previously published works, please review and evaluate these publications to determine whether they are relevant and should be cited. There is no requirement to cite these works unless the editor has indicated otherwise. 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. Additional Editor Comments: on: Minor Revision Dear Authors, Thank you for submitting your manuscript entitled “Beyond coverage: can vaccination reduce child mortality despite structural inequality? A global ecological analysis of routine childhood immunization (2010–2023)” to PLOS ONE. The manuscript has now been evaluated by two independent reviewers. Both reviewers find the topic timely and relevant and consider the analysis valuable for understanding the relationship between routine childhood immunization and child mortality in the context of structural inequality. They also agree that the manuscript is generally well written and methodologically sound. However, several minor revisions are required before the manuscript can be considered for acceptance. The reviewers have provided constructive suggestions aimed at improving clarity, strengthening the presentation of the methods and results, and enhancing the interpretation of findings. Please address each reviewer comment carefully and provide a detailed point-by-point response indicating how revisions have been made. When revising your manuscript, please ensure that: the methodological approach and limitations are clearly described, any language or structural issues highlighted by the reviewers are addressed. We look forward to receiving your revised manuscript. Sincerely, Academic Editor PLOS ONE [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: Yes ****** 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: The manuscrtpts topic is highly relevant, especially given ongoing global health disparities in immunization coverage, particularly how immunization mitigates mortality in unequal settings. The introduction effectively frames the topic's relevance, discusses equity gaps and states clear aims. Minor suggestions: - Delete duplicate 'for six' (line 78) - Change “accounting country level“ to “accounting for country-level” (line 76) for grammatical accuracy - Consider brief vaccine descriptions, noting targeted diseases, efficacy evidence, and known disparities in uptake amid structural inequalities. Listing the vaccines without context misses a chance to underscore their proven mortality reductions and equity challenges in low-resource settings Materials and Methods are well-described and appropriate, enabling reproducibility. Minor suggestions: - Clarify missing data exclusion threshold - Add statistical software and model diagnostics - Elaborate COVID-19 disruption handling. The results section is clearly presented, logically organized, and appropriately supported by the data, requiring no substantive revisions. The discussion is comprehensive, well-referenced, and balanced, with excellent integration of structural determinants. Minor suggestions: - Change "suggest" to "suggests" (line 324) for grammatical accuracy - Elaborate briefly on MCV2's later scheduling vulnerability The conclusions appropriately summarize findings and offer meaningful policy implications. Minor suggestion: - Change “highlights” to “highlight” (line 360) for grammatical accuracy Reviewer #2: Dear Authors, Thank you for your work. Please find below, some minor remarks you might like to address: 1. Line 77 "for six" repeats 2. The sentence starting on line 224 "Differences across..." needs to be rewritten because currently it looks like the p-value refers to BCG vaccination coverage, while you state it is the exception. 3. Line 253, all ⍴ < 0.001 - you should substitute the rho symbol with p as you are stating a p-value. 4. Line 288 - S1 and S2 are cited in the text so they shouldn't appear in the supplementary material section. Once removed numbers should be adjusted to match numbers in the suplementary materials file. 5. The csv-file (Table S1. Country–year analytical dataset (2010–2023).) is not accessible when downloading the supplementary materials. Kind regards ****** 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 ensure your figures meet our technical requirements, please review our figure guidelines: https://journals.plos.org/plosone/s/figures You may also use PLOS’s free figure tool, NAAS, to help you prepare publication quality figures: https://journals.plos.org/plosone/s/figures#loc-tools-for-figure-preparation. NAAS will assess whether your figures meet our technical requirements by comparing each figure against our figure specifications. https://doi.org/10.1371/journal.pone.0340756.r001
Revision 1
26 Mar 2026 Author Response Manuscript PONE-D-25-68661 Dear Editors and Reviewers: Thank you for the opportunity to submit a revised version of the manuscript “Beyond coverage: can vaccination reduce child mortality despite structural inequality? A global ecological analysis of routine childhood immunization (2010–2023)” for consideration in PLOS One. We are grateful for the time and effort provided, and we sincerely appreciate the feedback that has helped us to strengthen our manuscript. We have implemented the recommendations, and the revised manuscript highlights the corresponding changes. Reviewers' Comments to the Authors: Reviewer 1 1. Comment from Delete duplicate “for six” (line 78) Author response: Thank you for this observation. The duplicated phrase has been removed from the revised manuscript (line 78) 2. Comment to change “accounting country level“ to “accounting for country-level” (line 76) for grammatical accuracy Author response: Thank you for bringing this to our attention. We have revised the phrase to “accounting for country level” in line 76. 3. Consider brief vaccine descriptions, noting targeted diseases, efficacy evidence, and known disparities in uptake amid structural inequalities. Author response: Thank you for this valuable suggestion. A brief description of the vaccines included in the analysis, including the diseases they target and evidence supporting their effectiveness in reducing child mortality, has been added to the Data sources and variables section of the revised manuscript. “Vaccination coverage indicators included the proportion of children receiving Bacillus Calmette-Guérin (BCG), which protects against severe forms of childhood tuberculosis; the second dose of measles-containing vaccine (MCV2), targeting measles infection and typically administered during the second year of life (around 15 to 18 months); a later schedule is associated with an increased risk of missed follow-up visits and drop-out between measles vaccine doses in routine immunization programs [21-22]; and the third dose of diphtheria-tetanus-pertussis (DTP3), hepatitis B (HepB3), Haemophilus influenzae type b (Hib3), and poliovirus (Pol3) vaccines, which prevent major infectious diseases such as diphtheria, tetanus, pertussis, hepatitis B infection, invasive Haemophilus influenzae type b disease, and poliomyelitis, respectively. These antigens are the core components of routine child immunization programs and have contributed substantially to global reduction in vaccine-preventable child mortality. Despite this effectiveness, vaccination coverage remains uneven across countries, reflecting structural inequalities, including socioeconomic disadvantage, geographical barriers to healthcare access, and variations in health system capacity, particularly in low-income settings.” 4. Comment from Minor suggestions: - Clarify missing data exclusion threshold - Add statistical software and model diagnostics - Elaborate COVID-19 disruption handling. Author response: Thank you for these beneficial suggestions. We have addressed these points in the revised manuscript, specifically in the Materials and Methods section. “To ensure data quality and comparability, the integrity of country-year observations was evaluated across all variables; the number of missing values (NAs) per country ranged from 84 to 540 across the study period. Countries with more than one-third of the maximum observed number of missing values (>180 NAs) were excluded from the analysis. This threshold was applied to minimize bias from excessive missing data while the final analytical sample was restricted to countries meeting this inclusion criterion.” “ In addition, because routine immunization services were widely disrupted during the COVID-19 pandemic, the study period (2010-2023) was intentionally retained to capture both pre-pandemic trends and pandemic-related deviations in vaccine coverage. Rather than excluding these observations, country-year data from 2020 to 2023 were maintained to evaluate changes in coverage trajectories. Temporal trends were, therefore, interpreted considering this global disruption, which allowed the analysis to capture both the abrupt decline in vaccination coverage in 2020 and the subsequent partial recovery during 2021-2023.” “All statistical analyses were conducted using R version 2024.04.2. Model assumptions were evaluated through standard diagnostic procedures, including inspection of residual distributions and assessment of multicollinearity among predictors.” 5. Line 324: Change “suggest” to “suggests.” Author response: Thank you for pointing this out. The correction has been implemented in the revised version of the manuscript. 6. Elaborate briefly on MCV2’s later scheduling vulnerability. Author response: Thank you for this suggestion. A brief explanation regarding the later scheduling of MCV2 and its potential vulnerability to missed vaccinations or service disruptions has been added to the Data sources and variables section of the revised manuscript. “ …the second dose of measles-containing vaccine (MCV2) targets measles infection and is typically administered during the second year of life (around 15 to 18 months); a later schedule is associated with an increased risk of missed follow-up visits and drop-out between measles vaccine doses in routine immunization programs [21-22].” 7. Line 360: Change “highlights” to “highlight.” Author response: Thank you for pointing this out. The correction has already been made in the revised version of the manuscript. Reviewer 2 Dear Authors, Thank you for your work. Please find below, some minor remarks you might like to address: 1. Line 77 "for six" repeats Author response: Thank you for pointing this out. The correction has already been made in the revised version of the manuscript. 2. The sentence starting on line 224 "Differences across..." needs to be rewritten because currently it looks like the p-value refers to BCG vaccination coverage, while you state it is the exception. Author response: We agree with the reviewer’s suggestion. The correction has already been made to make it clearer that we wanted to state it was the exception. 3. Line 253, all ⍴ < 0.001 - you should substitute the rho symbol with p as you are stating a p-value. Author response: Thank you for pointing this out; the rho symbol has already been replaced with “p”. 4. Line 288 - S1 and S2 are cited in the text so they shouldn't appear in the supplementary material section. Once removed numbers should be adjusted to match numbers in the supplementary materials file. Author response: The reviewer does not clarify if they are referring to S1/S2 Table or S1/S2 Figure; however, none of them are cited in the text, especially not in line 288, so we are not sure of what the reviewer is referring to. 5. The csv-file (Table S1. Country–year analytical dataset (2010–2023). is not accessible when downloading the supplementary materials. Author response: The table the author is referring to is Table S3 in the CSV file. The code writes two CSV files that can be opened in Excel so that they are understandable. The code writes two CSV files that can be opened in Excel in order for it to be understandable. Attachments Attachment Submitted filename: Response to Reviewers.docx https://doi.org/10.1371/journal.pone.0340756.r002
21 Apr 2026 Decision Letter - Vanya Rangelova, Editor <p>Beyond coverage: can vaccination reduce child mortality despite structural inequality? A global ecological analysis of routine childhood immunization (2010–2023) PONE-D-25-68661R1 Dear Antonio Marty Quispe 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 will be generated when your article is formally accepted. Please note, if your institution has a publishing partnership with PLOS and your article meets the relevant criteria, all or part of your publication costs will be covered. Please make sure your user information is up-to-date by logging into Editorial Manager at Editorial Manager® and clicking the ‘Update My Information' link at the top of the page. For questions related to billing, please contact billing support. 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, Vanya Rangelova, M.D., Ph.D. Academic Editor PLOS One Additional Editor Comments (optional): Dear Authors, Thank you for submitting your manuscript entitled “Beyond coverage: can vaccination reduce child mortality despite structural inequality? A global ecological analysis of routine childhood immunization (2010–2023)” to PLOS ONE. I have now carefully considered the revised version of your manuscript, the reviewers’ comments, and your detailed responses to the points raised during peer review. I am pleased to inform you that your manuscript has been accepted for publication in PLOS ONE. Both reviewers found the study to be timely, relevant, and methodologically sound, and they considered the revisions to have adequately addressed the minor concerns raised in the initial review round. Your responses were clear and constructive, and the revised manuscript has been strengthened accordingly. This study makes a valuable contribution to the literature by examining the relationship between routine childhood immunization coverage, structural inequality, and child mortality at a global scale over an extended time period. The findings provide important evidence for researchers, policymakers, and public health practitioners seeking to understand how vaccination programs may contribute to improved child survival outcomes even in settings marked by persistent socioeconomic disparities. On behalf of the journal, I thank you for choosing PLOS ONE for the dissemination of your work. We appreciate your contribution and look forward to seeing your article published. With best regards, Vanya Rangelova Academic Editor Reviewers' comments: https://doi.org/10.1371/journal.pone.0340756.r003
Formally Accepted
Acceptance Letter - Vanya Rangelova, Editor PONE-D-25-68661R1 PLOS One Dear Dr. Quispe, I'm pleased to inform you that your manuscript has been deemed suitable for publication in PLOS One. Congratulations! Your manuscript is now being handed over to our production team. At this stage, our production department will prepare your paper for publication. This includes ensuring the following: * All references, tables, and figures are properly cited * All relevant supporting information is included in the manuscript submission, * There are no issues that prevent the paper from being properly typeset You will receive further instructions from the production team, including instructions on how to review your proof when it is ready. Please keep in mind that we are working through a large volume of accepted articles, so please give us a few days to review your paper and let you know the next and final steps. Lastly, if your institution or institutions have a press office, please let them know about your upcoming paper now to help maximize its impact. If they'll be preparing press materials, 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. You will receive an invoice from PLOS for your publication fee after your manuscript has reached the completed accept phase. If you receive an email requesting payment before acceptance or for any other service, this may be a phishing scheme. Learn how to identify phishing emails and protect your accounts at https://explore.plos.org/phishing. If we can help with anything else, please email us at customercare@plos.org. Thank you for submitting your work to PLOS ONE and supporting open access. Kind regards, PLOS ONE Editorial Office Staff on behalf of Dr. Vanya Rangelova Academic Editor PLOS One https://doi.org/10.1371/journal.pone.0340756.r004

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 .