PONE-D-24-42834“We have to amplify what we saw at EBOVAC” – A mixed methods approach to assess participant acceptability of ancillary care in an Ebola vaccine trial in the Democratic Republic of the CongoPLOS ONE

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Additional Editor Comments:

Dear Authors, the manuscript needs minor revisions, please respond point by point to the reviewers' requests.

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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: This paper describes the participant experiences in an Ebola vaccine trial. Health care availability is poor in the region and the study determined that an ancillary care program would be helpful for participants. however, this was not implemented until later in the study.

1. The team should do more to clarify the timeline of initial vaccinations and boosters to the availability of the AC program. With the program starting in the final year of the program - it seems to be after the time when most would experience treatment related AEs. It is not clear if the AEs and SAEs being evaluated are study related in general, or if they are health problems experienced by participants (for instance, there is apparently a leg injury in the study and that seems unlikely to be trial related). It is not necessarily important to know which are related or not. But surely, care for related AEs would be considered the highest priority for the study.

2. The timeline in figure 1 is not clear. The big bubbles are colorful, but are not lined up with the time period during which they were administered. When were study events, first vaccines, booster vaccines? Are they all completed by the time the AC was implemented? The colored bars are not as obviously associated with the different bubbles and I only noticed they were numbered after staring at the figure for some time. The bubbles are also not relative in size to the sample size and thus a bit misleading. 17 interviews should have a much smaller bubble.

3. The bar graphs of the survey responses are not all necessary. The telephone survey results do not need a bar graph - everyone was happy. The Q1-6 is nice, the Q7-8 and Q10 are also not very informative. Q9 does have more diversity of answers, but it is equally well represented in the text.

4. a. Table 1 is confusing in parts. There are 700 participants in the vaccine study, with 370 individuals reporting an AE? Or 370 reported AEs?

b. 185 of those surveyed - our of 290? - had an AE.

c. What are the demographics of the surveyed participants who did not have an AE? Two columns would be good for that category as is done for the telephone interviews.

d. Then the telephone survey participants are divided by with and without an AE, but one group is without self-reported AE, and with self reported unsupported AE. Were the ones without a self-reported AE eligible for care, if they had needed it?

e. The racial distribution seems unnecessary as the study was all Black Africans.

f. The differences in AEs by sex are striking. Given the differences in self-report bias that might occur in this study it seems appropriate to discuss these differences. Men made up 3/4 of those with AEs. How does this relate to the overall study sample?

g. What does "medical history" refer to in the table? It is different by groups.

h. what are arms 1 and 2? Did the Arm 2 participants get any injections while the study was underway?

5. The study is a very nice evaluation of perceptions. I imagine there is heavy bias towards socially desirable reporting. This was mentioned in the discussion, but ways to mitigate this should be considered for future studies. Anonymous reporting might be less biased. The telephone interviews show a strong leaning towards that. But in an area with little health care, the AC program was probably very helpful. One element the study team should discuss a bit more is the disconnect between the perceptions of what the AC program was for - and what the participants wanted or expected. Establishing reasonable expectations is key when enrolling participants. The concept that the AC program was not "long lasting enough", that they would be gone tomorrow, that is a key misconception. And these participants were associated with the health care setting - many being CHWs and professionals. If these participants were misinformed, it is vital that programs do an even better job instructing their participants as to what they might expect.

6. There are a lot of quotes from participants, some may even be identifying. How many people had a serious leg injury in the study? It seems that the study team might want to obscure that a bit more. The editors may wish to reduce the number of quotes - but they are interesting and informative. Usually one doesn't get to see the primary results. I enjoyed reading them.

The paper is well written, the writing style is clear and easy to read. I anticipate that the study team can make the tables and figures more crisp and address some of the confusion around the parent study timeline and the AC evaluation timeline.

Reviewer #2: The authours have addressed an important topic and sused appropriate methods.However the follwing areas should be addresed/clarified:

1.The tittle should be revised to capture what is written in the manuscript.Thoughout the manuscript,in addition to acceptability,the words perception,attitudes and even safisfaction come up.These should be included in the title especially attitudes and percecption,the opening statement of the discussion section,makes a good case for their nclusion in the title. In addition the word``policy ``should be added to ancillary care in the tittle.

2.In the abstract,the indroduction should be beefed up,they authours cang et a brief statement from the first paragraph of the main intoduction. The study objective should also be stated in the abstract.

3.The introduction was well staed but the objectives which have been stated in lines 85-88and that in lines91-92 should be harmined and sorted out which ones fit well with the study and study tittle.and the objectives should stated at the end of the introduction.The statement ``This paper............among trialparticipnts`` can beleft out

4.Study design,sampling and data collection: The methods from lines 101-159 need to be revised and state clearly how the interviews were conducted and how the participants for diferent intreviews were selected andhow many were allocated for each surveyand whic questions wre asked, on the contrary,fromthe results,it indicates the partipants were responding to specific questions.In the methods the numbers of study participants shoud be clearly statedi because it comes a challenge when it comes to the results section.The diffent cadres of health workersare not stated in themothods but they appear in the resuktsintable 1.who are`frontliners?``

5.Results:At the begining of te results section the numbersof the total study participnts and the different categories are not stated. Howver in table 1 on the social demographic and baeline charactersoistics, these numbers comeup.The othaurs should clearly clarify n these bnumbsers fr exampleinthe astract it says the total number of participants whohad AEs were 185 !! As stated in the methods section these numbers should be clarified.

Otherwise the results werefairly wellp resented.however in some instances,the results are mixed with methods,the me thods shouldnt be includ ed in the results e.g lines 217-225,methods are being mentined together with results,same case with lines 239-244. Also in the qualitative results,there is need to teese out the results from what was presented.

e.g.lines323-326and 340-343. Is possible to further summerise the this section?

6.Discussion:Theauthur discussed teir results well .However is the state inline 378-380 and refering totable results from their study or recomanation,let it be put in appropriate section.it is unsuual to have a table in thediscusionsection.

7.Conclusions&recommedations:Thesshould be revised to be in line with te study ttile and objectives and study resukts respectively.

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Reviewer #1: No

Reviewer #2: Yes: MworoziEdison Arwanire

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“We have to amplify what we saw at EBOVAC” – Assessing Participant Perceptions, Attitudes, and Acceptability of an Ancillary Care Policy in an Ebola Vaccine Trial in the Democratic Republic of the Congo: A Mixed Methods Study

PONE-D-24-42834R1

Dear Dr. Lemey,

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.

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Kind regards,

Omar Enzo Santangelo

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 #2: 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 #2: Yes

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3. Has the statistical analysis been performed appropriately and rigorously?

Reviewer #2: Yes

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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 #2: No

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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 #2: 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 #2: The authours have appropriately addressed and responded to all the comments/recommendations by the reviewers.

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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.

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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 #2: Yes: Edison Mworozi Arwanire

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