Review Reports

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The topic is relevant to policymakers and program managers. This manuscript provides relevant information which can be used by countries that are transitioning to the hexavalent vaccine. The title reflects the content of the manuscript. The introduction orients the readers to the topic and states the aim of the manuscript. The methodology used in the study is clearly discussed to allow for the replication of the study. The findings are clearly presented with the help of tables. The discussion should be strengthened with comparison of literature from other LMICs.

MAJOR REVISION

Methodology

1. In line 177, the authors state, ‘This analysis constitutes non-human subjects research.’ This statement is not correct since there were human participants. I suggest it be removed or rephrased. I think the authors want to justify that there was no need of ethical approval from an IRB, which can be done differently.

Discussion

2. The authors should compare their findings with those of other regions that have moved from the pentavalent to the hexavalent vaccine.

MINOR REVISIONS

1. In line 148, write MEL in full.
2. In line 169, provide a citation for the framework.
3. In line 182, include AI in brackets.
4. In Figure 2, AEFI should be written in full.
5. In line 316, DHIS2 should be defined.
6. In line 378, the authors state, ‘Persistently difficult-to-access moughataas.’ The sentence is not complete.

Author Response

Comment 1: "In line 177, the authors state, ‘This analysis constitutes non-human subjects research.’ This statement is not correct since there were human participants. I suggest it be removed or rephrased. I think the authors want to justify that there was no need of ethical approval from an IRB, which can be done differently."

Response: Thank you for identifying this error. We have fixed it and replaced it with "This manuscript reports proceedings and discussions from a technical workshop and does not present findings from human subjects research; therefore, institutional ethics review was not required." (line 194)

Comment 2: "The authors should compare their findings with those of other regions that have moved from the pentavalent to the hexavalent vaccine."

Response: Thank you for this important comment, which we believe will strengthen the paper. We included more context from global picture in the Discussion (line 548), specifically: "The Hexavalent Switch Early Adopters Workshop focused on the African continent but it follows the experiences of more than 56 countries that use hexa vaccines globally. Key country findings from hexa switch countries primarily outside of Africa demonstrated that hexa vaccines improved immunization compliance, timeliness and coverage. Global lessons include considering vaccine availability, vaccination schedules, health system readiness, HCP training, vaccine acceptance and infrastructure and resources in advance of hexa switches [8]—themes that also emerged in the Early Adopters workshop. "

Comment #3: Minor Revisions: "

1. In line 148, write MEL in full.
2. In line 169, provide a citation for the framework.
3. In line 182, include AI in brackets.
4. In Figure 2, AEFI should be written in full.
5. In line 316, DHIS2 should be defined.
6. In line 378, the authors state, ‘Persistently difficult-to-access moughataas.’ The sentence is not complete."

All minor revisions were addressed as suggested in their respective line items.We appreciate the time you took to give this thoughtful review. With it, it made the manuscript better, and we hope it will be useful to more readers.

Reviewer 2 Report

Comments and Suggestions for Authors

A 2025 workshop in Dakar convened representatives from 10 African countries to accelerate the transition from separate pentavalent and IPV vaccines to the combined hexavalent vaccine. Early adopters (Mauritania, Senegal) shared real-world data showing operational feasibility, reduced injection burden, and logistical efficiencies, though coverage varied due to seasonal factors and system constraints. Participating countries identified shared vulnerabilities: stock coexistence risks, data completeness gaps, under-resourced adverse event surveillance, and financing uncertainties under Gavi 6.0. The workshop produced three co-created tools: a Health System Adaptation Checklist, a Switch Risk Mitigation Catalog, and country-specific 12-month roadmaps. Findings indicate that structured regional peer-learning mechanisms can accelerate evidence-informed decision-making, improve implementation quality, and strengthen accountability. The authors conclude that collaborative cross-country models turn product switches into scalable opportunities to strengthen systems, offering a blueprint for future vaccine introductions in Africa and beyond.

The following issues should be addressed before publication:

1. Table 2 is highlighted by an editor’s comment as “quite long and detailed”. Is it possible to convert Table 2's content into a schematic diagram format? or moved to an appendix.
2. The results section (e.g., detailed Mauritania/Senegal coverage data) overlaps with planned post‑introduction evaluation manuscripts. Trimming these specifics and focusing on cross‑cutting lessons would improve conciseness.
3. The limitations section mentions purposive sampling and self‑reported data, but it does not address potential social desirability bias in workshop discussions or the lack of independent verification of country claims.

Author Response

Comment #1: "Table 2 is highlighted by an editor’s comment as “quite long and detailed”. Is it possible to convert Table 2's content into a schematic diagram format? or moved to an appendix."

Response: Thank you for this feedback. We have developed a schematic diagram format of the same table, which will improve readability. (line 636)

Comment #2: "The results section (e.g., detailed Mauritania/Senegal coverage data) overlaps with planned post‑introduction evaluation manuscripts. Trimming these specifics and focusing on cross‑cutting lessons would improve conciseness."

Response: Thank you for this important observation. We trimmed extraneous detail from both Mauritania and Senegal results and focused on the most salient points. (lines 361-450)

Comment #3: "The limitations section mentions purposive sampling and self‑reported data, but it does not address potential social desirability bias in workshop discussions or the lack of independent verification of country claims."

Response: Thank you for this comment. We have addressed it in the Limitations section and included the sentence: "Much of the evidence is based on self-reported country data shared during workshop discussions and planning exercises; while triangulated through peer exchange and facilitation with ideas and contributions written down and contributed anonymously by participants, these data may be subject to social desirability bias, reporting bias, variable quality, and limited or incomplete  documentation, and preliminary country data results, particularly for early implementation of three months or less and subnational outcomes." (line 648)

We appreciate the time taken to review this paper. With your comments, the manuscript is stronger and we hope will be useful to more readers.

Reviewer 3 Report

Comments and Suggestions for Authors

This is a report of a workshop. The most relevant question is whether it correctly reflects the discussions in and contributions to this workshop. Given that 30 authors have signed for the manuscript, it can be assumed that it does. I have only two questions:

• Were the experiences with the hexavalent vaccine of non-African countries in some way represented during the workshop?
• How do the authors relate to the other delegates at the workshop (assuming there were others)? E.g., were they delegation leaders or do they in some way formally represent country or organization delegations?

Author Response

Comment #1: "Were the experiences with the hexavalent vaccine of non-African countries in some way represented during the workshop?"

Response: They were not. However, to give context, we included some global data in the Discussion section: "The Hexavalent Switch Early Adopters Workshop focused on the African continent but it follows the experiences of more than 56 countries that use hexavaccines globally. Key country findings from hexa switch countries primarily outside of Africa demonstrated that hexa vaccines improved immunization compliance, timeliness and coverage. Global lessons include considering vaccine availability, vaccination schedules, health system readiness, HCP training, vaccine acceptance and infrastructure and resources in advance of hexa switches [8]—themes that also emerged in the Early Adopters workshop. " (line 548)

Comment #2: "How do the authors relate to the other delegates at the workshop (assuming there were others)? E.g., were they delegation leaders or do they in some way formally represent country or organization delegations?"

Response: Thank you for this comment. A line to clarify the role of the authors as participants was added (line 181): "This manuscript’s co-authors represented countries and organizations participating in the workshop and contributed to synthesizing the workshop’s above outputs. "

Thank you for taking the time to review this paper, we appreciate it.

Reviewer 4 Report

Comments and Suggestions for Authors

Thank you for a very well structured manuscript, please address the below points:

• In the introduction, it is unclear why the meeting was held in this particular location, if there is any specific reason please incorporate to the text (one presumes it is because Senegal is an early adopter, but has to be mentioned more clearly).
• In the introduction there is little mention on potential cost implications. As a large part of thee decision making process will be system- and cost-driven, it would merit to add 1-2 additional sentences regarding the cost aspect to the introduction.
• In the methods section, please mention how the ten 'process points' were selected, or provide the relevant reference. These are the common points, but would be good to anchor the description to the literature.
• In the results section, why was a 12 month roadmap proposed as opposed to a longer period? The real-world case studies showed that 12 months are probably an ambitious target for some countries.
• The discussion could be improved by adding some 'last mile logistics' examples from other vaccination initiatives. It is perhaps not an ideal comparison, but given the data gaps, it is acceptable to use such examples where possible.
• The conclusion can mention that such an initiative can be more regular and systematic, as the results of the workshop seem to be indeed quite useful to the different countries attending.

Author Response

Comments #1: "In the introduction, it is unclear why the meeting was held in this particular location, if there is any specific reason please incorporate to the text (one presumes it is because Senegal is an early adopter, but has to be mentioned more clearly)."

Response: Thank you for the comment. Yes, we clarified the rationale for the location in line 99: "Recognizing these needs, the Sabin Vaccine Institute and the World Health Organization Regional Office for Africa (WHO AFRO) convened the Hexavalent Vaccine Switch Early Adopters Workshop in Dakar, Senegal, an early adoptor of the hexa vaccine, in November 2025."

Comment #2: "In the introduction there is little mention on potential cost implications. As a large part of thee decision making process will be system- and cost-driven, it would merit to add 1-2 additional sentences regarding the cost aspect to the introduction."

Response: Thank you for this important feedback. We have incorporate additional context on costing into the introduction as suggested: "Costing is central to this transition because countries must account not only for vaccine price and co-financing obligations, but also for the operational costs of readiness, including cold chain adaptation, supply chain reconfiguration, health worker training, communication, supervision, monitoring tools, and transition-period stock management. These costs are often distributed across budget lines and partners, making early, comprehensive costing essential for realistic planning, domestic resource mobilization, and sustainable implementation." (line 79)

Comment #3: "In the methods section, please mention how the ten 'process points' were selected, or provide the relevant reference. These are the common points, but would be good to anchor the description to the literature."

Response: Thank you for this observation. We have added the relevant reference: "World Health Organization. Monitoring the building blocks of health systems: a handbook of indicators and their measurement strategies. Geneva: World Health Organization; 2010. " 

Comment #4: "In the results section, why was a 12 month roadmap proposed as opposed to a longer period? The real-world case studies showed that 12 months are probably an ambitious target for some countries."

Response: Thank you for this response. We had added further context and rationale (line 472): "Third, countries developed a country-specific 12-month roadmap for hexa vaccine introduction, optimization, or post-introduction evaluation, although some countries planned introduction beyond 12 months and focused their roadmap on early-stage planning."

Comment #5: "The discussion could be improved by adding some 'last mile logistics' examples from other vaccination initiatives. It is perhaps not an ideal comparison, but given the data gaps, it is acceptable to use such examples where possible."

Response: Thank you for this comment. We have added the following context (line 566): "For example, challenges many EPI programs face with “last mile logistics” also can affect hexa switch, risking efforts to leverage hexa to reduce numbers of zero-dose children. "

Comment #6: "The conclusion can mention that such an initiative can be more regular and systematic, as the results of the workshop seem to be indeed quite useful to the different countries attending."

Response: Thank you, we have added this language (line 626): "As countries continue to adapt immunization schedules to emerging evidence and evolving financing landscapes, such in-person regional learning mechanisms may prove an essential standing mechanism for strengthening policy to best practice in immunization programs and could become more regular and systematic."

We appreciate your valuable time given to review our manuscript. It is a stronger paper for it.

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

The authors have satisfactorily addressed all my comments.