Social Determinants and Outbreak Dynamics of the 2025 Measles Epidemic in Mexico: A Nationwide Analysis of Linked Surveillance Data

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

This is a very interesting and well written manuscript. However, it is very lengthy and would be greatly improved if shortened significantly.

Introduction: quite long, could be shortened.

Lines 60-77 are not really necessary and could be deleted. No added value. 

Materials and Methods

Table 2, Line 455. Please clarify numbers in second top row of table. What do they represent? Number of municipalities?

The Materials and Methods section is too long and should be shortened.

The Results section is too long with duplication of information in the text and some of the tables. It may be more useful to move the raw data tables to the supplement section.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

Very Respected Authors,

The abstract is well structured. The introduction provides sufficient information relevant to the topic of the paper. The objective is clearly stated. The methodology is described in detail, and an appropriate study design was selected. The study methodology is comprehensive, and the authors used multiple sources of information to address the main objective of the paper in depth. The results are clearly presented. Tables and figures are provided in the supplementary file. The discussion is well written, and the results are compared with existing findings. The conclusion is  in agreement with the objective and results of the paper.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

Report for

Type of manuscript: Article
Title: Social Determinants and Outbreak Dynamics of the 2025 Measles Epidemic in Mexico: A Nationwide Analysis of Linked Surveillance Data
Journal: Viruses

Un this article the authors conducted a nationwide analysis of Mexico's 2025 measles outbreak, using individual-level surveillance data from a Special Surveillance System that has municipal-level social determinants from eight national databases. In addition, used molecular surveillance data. The authors analyzed 6151 confirmed cases (epidemiological weeks 8–52, 2025) using spatial autocorrelation (Moran’s I, LISA), effective reproduction number estimation, negative binomial regression, and logistic regression for risk factors.

 The results show cases concentrated in Chihuahua (73%), with 45 LISA hot-spot municipalities containing 71.68% of cases. Molecular surveillance confirmed two independent introductions: D8/MVs/Ontario.CAN/47.24 (98.1%) linked to the Canadian outbreak, and B3 (1.9%) in Oaxaca.

The authors mentioned that the transmission followed a three-stage pattern: introduction through seasonal agricultural worker networks, amplification in undervaccinated communities, and diffusion to marginalized indigenous populations.

The authors mentioned that vaccine effectiveness was 98.2%, with 83.4% of cases in pockets of susceptibles (municipalities with ≥80% unvaccinated).

Risk factors for complications included age <5 years (aOR 3.59), indigenous status (aOR 2.35), and unvaccinated status (aOR 2.03). Indigenous individuals comprised 30% of cases but 76% of 34 deaths.

The authors concluded that national vaccination thresholds are insufficient when marginalized populations remain systematically underserved.

The topic is relevant to public health and the authors gather important information. The authors analyzed the data to reach some conclusions. The article needs some improvements.

In the abstract it is not clear the sentence: “Vaccine effectiveness was 98.2%, with 83.4% of 31 cases in pockets of susceptibles (municipalities with ≥80% unvaccinated).”

Page 2. Not sure why the authors mentioned outbreaks until 2023, instead of 2026. Recently there have been several outbreaks in the USA. The authors should mention some of the previous measles outbreaks to provide a relation with the Mexico outbreaks. Especially since the authors concluded that cases were imported from Canada despite the USA is much closer and there were outbreaks in border USA states.

“Between 2019 and 2023, 18 countries in the Americas experienced measles outbreaks”

Page 3. Authors mentioned data coverage from weeks 1-52, but in abstract says 8-53.

Line 72. Recently it has been mentioned that vaccine coverage reports might have inaccurate data. Please comment on this.

Line 220. Even Rt is well-known it would be good to explain the specific computation for all the readers.

Check line 253.

Line 277. Why MCV1 until 2023.

Line 295. P<0.2. Explain this choice. Is not too high?

Line 353. Please explain how 78% of Chihuahua cases were labeled as imported. Other states only 23%. Since Chihuahua states it shares an extensive border with the U.S. states of New Mexico and Texas, can this result be related to the 2025 outbreak in those US states. Comment on this. Connect with line 680.

Paragraph 400. Comment on why other states had much lower Rts.

Please explain how the variable in the y-axis of figure 3c is computed. Local Moran I statistic.

Line 450. Seems contradicting that despite a large number for imported cases, then affected municipalities concentrated in low-to-medium migration categories. Someone would expect high migration rates.

Table 2 is not clear. For example, Mean of 51,038 and SD 146,990? This will provide negative values. Is confusing.

Line 680. Since the Rt of Chihuahua was high in comparisons with other Mexican states and the authors mentioned overlap with Texas and New Mexico US states, it would be good to compare and discuss the Rt with this outbreak.

Line 697. Similar to the previous comment but now regarding vaccination coverage.

Line 721. Excellent scientific practice by mentioning limitations of this work.

I commend the work done by the authors. The analysis is well done and shows a lot of interesting results. The genome sequencing is excellent.

Minor typos:

Check lines 54-61-63 and more. Leave space before references.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Round 2

Reviewer 3 Report

Comments and Suggestions for Authors

The authors did an excellent work addressing the questions raised by this reviewer. The only aspect that might be improved is the comparison of Rt with the related measles outbreak on Texas 2025 (since the authors mentioned it). The authors compared with other measles outbreaks from 2019 and 2023. The article [1] includes some results regarding Rt.

In the discussion the authors have:

“VE comparison with USA: Our VE estimate (98.1%, 95% CI: 98.0-98.2%) is consistent with estimates from recent US outbreaks: the 2019 New York City outbreak reported two-dose VE of 97.2% (Rosen et al., Pediatrics 2023),”

[1] González-Parra, G., Vestrand, A., & Mujynya, R. (2025). Modeling and Characterizing the Growth of the Texas–New Mexico Measles Outbreak of 2025. Epidemiologia, 6(4), 60.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf