PONE-D-22-12508Immunogenicity and reactogenicity of a third dose of BNT162b2 vaccine for COVID-19 after a primary regimen with BBIBP-CorV or BNT162b2 vaccines in Lima, Peru.PLOS ONE

Dear Dr. Vargas Herrera,

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 all the points raised during the review process.

Please submit your revised manuscript by Aug 12 2022 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 rebuttal 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,

Daniela Flavia Hozbor

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. Please include captions for your Supporting Information files at the end of your manuscript, and update any in-text citations to match accordingly. Please see our Supporting Information guidelines for more information: http://journals.plos.org/plosone/s/supporting-information. 

3. Thank you for stating the following financial disclosure: 

 "Yes, this study was funded by the Instituto Nacional de Salud del Peru, study protocol number OI-035-2021." 

Please state what role the funders took in the study.  If the funders had no role, please state: "The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript." 

If this statement is not correct you must amend it as needed. 

Please include this amended Role of Funder statement in your cover letter; we will change the online submission form on your behalf.

4. We note that you have indicated that data from this study are available upon request. PLOS only allows data to be available upon request if there are legal or ethical restrictions on sharing data publicly. For more information on unacceptable data access restrictions, please see http://journals.plos.org/plosone/s/data-availability#loc-unacceptable-data-access-restrictions. 

In your revised cover letter, please address the following prompts:

a) If there are ethical or legal restrictions on sharing a de-identified data set, please explain them in detail (e.g., data contain potentially sensitive information, data are owned by a third-party organization, etc.) and who has imposed them (e.g., an ethics committee). Please also provide contact information for a data access committee, ethics committee, or other institutional body to which data requests may be sent.

b) If there are no restrictions, please upload the minimal anonymized data set necessary to replicate your study findings as either Supporting Information files or to a stable, public repository and provide us with the relevant URLs, DOIs, or accession numbers. For a list of acceptable repositories, please see http://journals.plos.org/plosone/s/data-availability#loc-recommended-repositories.

We will update your Data Availability statement on your behalf to reflect the information you provide.

5. Please include captions for your Supporting Information files at the end of your manuscript, and update any in-text citations to match accordingly. Please see our Supporting Information guidelines for more information: http://journals.plos.org/plosone/s/supporting-information. 

[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: Partly

Reviewer #2: Partly

**********

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: No

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: No

**********

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: In this manuscript, Vargas-Herrera and colleagues investigate the response to a BNT162b2 booster vaccination in elderly individuals previously immunized with BNT162b2 as well as younger health care workers previously vaccinated with the inactivated BBIBP-CorV vaccine. To this end, reactogenicity was assessed and SARS-CoV-2-reactive IgG levels were determined on the day of and 14 days after the booster dose.

The authors demonstrate that an mRNA-based booster dose is generally well tolerated and that it induces a strong increase in SARS-CoV-2-reactive IgG levels. This effect is more pronounced in individuals that received a heterologous vaccination regimen.

The results of this study recapitulate the findings of numerous earlier studies, both on tolerability and humoral immunity, and extends them to cohorts from Peru. The results are overall plausible and in line with the results of previous studies. Most of the limitations of the study are acknowledged by the authors. Because the BBIBP-CorV vaccine is widely used but relatively little studied compared to other vaccines, analyzing the effects of booster vaccinations after a primary BBIBP-CorV dose is important.

There are several aspects that I would suggest the authors to address in a revised version of the manuscript.

Major comments:

1)

IgG levels are determined using an assay that tests for reactivity against both the spike protein and the nucleoprotein of SARS-CoV-2 without differentiating this reactivity. Because the BBIBIP-CorV vaccine is an inactivated whole virus vaccine, it will induce antibodies against both proteins (spike and nucleoprotein). In contrast, the BNT162b2 mRNA vaccine exclusively induces antibodies against the spike. This complicates comparisons of the IgG levels as the assay used will pick up two classes of antibodies after BBIBP-CorV vaccination but only class after BNT162b2 vaccination. Ideally, samples would be analyzed using an IgG assay that determines only spike reactivity. Alternatively, could the contribution of anti-N antibodies to the determined signal be analyzed for a representative subset of samples? At a minimum, the use of a dual-reactive assay should be discussed as a limitation for the interpretation of this study.

2)

Immunogenicity results are provided as AU/ml (arbitrary units/ml). To facilitate comparison to results of other trials, it would be helpful if a conversion factor to the international standard BAU/ml using the WHO reference sample with this assay could be provided.

3)

Lines 224-226: Numbers in the text (RR 1.13, 95% CI 1.02-1.26) do not match numbers in Table 2 (female gender, adjusted model; RR 1.12, 95% CI 1.01-1.25)

4)

Lines 243-245/Table 3: The higher baseline titers in older individuals are not unexpected as the majority of elderly individuals had received primary immunizations with the much more immunogenic BNT162b2 vaccine. This should be pointed out here. Because the BNT162b2 is overall more immunogenic than the BBIBP-CorV vaccine, it would be helpful to have Table 3 (or an additional table) be split up into the different primary vaccines as well.

5)

Lines 338-342: While protection induced by inactivated virions could potentially be wider, the statement in its current form is a bit misleading as the lower protection of inactivated virion vaccines compared to the highly immunogenic mRNA vaccines seems well established.

6)

Lines 349-351: The authors state that antibody titers before the booster inversely correlated with the post-boost titers, suggesting that shorter boosting intervals may not be beneficial. In this study, this observation is very likely to be confounded by the fact that young individuals, which generally respond to the BNT162b2 vaccine with higher IgG titers than older individuals, had received the much less immunogenic BBIBP-CorV vaccine first. This results in the relatively strong increase in younger individuals (poorly immunogenic first vaccine, very strong response to booster). In contrast, older individuals had higher baseline titers due to the more immunogenic BNT162b2 vaccine compared to BBIBP-CorV (although titers in younger individuals receiving BNT162b2 would have been even higher), and then responded less strongly to the BNT162b2 booster dose than younger individuals.

Additional comments

7)

Table 1: While i.) the elapsed time between the second vaccine dose and the booster dose as well as ii.) the time between the the booster dose and the follow-up visit are described, information of the time between the first and second dose is missing (line 86 says: at least 21 days apart). As prolonged vaccination intervals are known to affect the humoral vaccine response, it would be helpful for the interpretation of the results and comparison of the groups to also include this measure.

8)

Table 1: Make clear within the table what groups the p values are comparing

9)

Figure 2: Instead of the natural logarithm, it appears advisable to display the data in the much more commonly used log10 format, which will help with comparison to other results. In addition, the legend needs to define lines, boxes and whiskers.

10)

Figure 3: The 95% confidence intervals are a bit difficult to make out and it would be helpful to display them in a more prominent shade of grey.

11)

Line 65: “13% fold” does not make sense

12)

Line 67: Make clear what “both” is referring to

13)

Line 144: Typo, should be BNT162b2

14)

Line 144-145: Beyond “mild” and “severe”, CTCAE also has a “moderate” classification. Was it deliberately excluded?

15)

Line 201: Ranged would be a better word than oscillated

16)

Lines 212-213: Better to write that there were “no statistically significant” differences than just “no” differences.

17)

Line 221: Better: nausea than nauseas

18)

Line 309: The lower antibody levels could also be expected because of the overall lower immunogenicity of the BBIBP-CorV vaccine compared to BNT162b2.

19)

Line 331-332: Heterologous vaccines are common ‘practice’ for several of the diseases (e.g., HIV, HPV). ‘Has been investigated’ might therefore be a better choice of words than ‘has been practiced’.

20)

Line 376: While the authors rightfully acknowledge the lack of analyses on neutralizing serum titers as a limitation of the study, the term ‘broadly’ for the description of the extend of humoral response measurements seems to wide to me (it is a rather narrow measurement of the humoral response). One could rather write “overall binding reactivity” or something similar.

21)

Line 395: “In addition, the antibody titers rising trend after the second vaccine dose in our study indicates that subsequent boosters could be spaced and prioritized in certain populations such as elderly and immunosuppressed.” I am not entirely sure what this statement is referring to. Trends after the second vaccine dose (prior to the booster) were not investigated. Should this refer to the higher titers after the booster dose compared to after the second vaccine dose?

Reviewer #2: Thanks for the opportunity to review.

I have a few comments regarding the manuscript that should be addressed.

- Overall the manuscript is written with a reasonable standard of english but could do with a thorough grammar edit.

The study is interesting, but it is difficult to draw any major conclusions about the impact of booster vaccines for the following reasons:

- It is expected that there would be such an increase in antibody titres early after a booster dose, 2 weeks is too early to assess immunogenicity and durability of response and a later sample would be more meaningful in response interpretation.

- Only IgG was measured, not neutralising antibody which may be more accurate in interpreting immune response correlating with protection

- In view of this is is preferable to tone these findings down as unfortunately it may be misleading to say that these responses result in protection and to correlate them to protection. The findings are interesting, but need to be focussed on what can be derived, rather than making assumptions

- There are also substantial differences between the homologous and heterologous groups and a comparison is very difficult even with some parameters controlled for

In addition:

- How was fever assessed?

-Was any formal measurement of local reactogenicity conducted (measure size of swelling, erythema etc.) Was FDA guidance used to evaluate this?

- How was prior COVID-19 assessed, given that it is expected that by Dec 21 close to 80% of the global population had been infected with COVID-19 as evidenced by antibody testing. Even asymptomatic infection would give an Ab response and this is likely to confound baseline data.

- In line 225 heterologous has been duplicated- I'm assuming that homologous is the correct term

There are significant differences

**********

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.]

While revising your submission, please upload your figure files to the Preflight Analysis and Conversion Engine (PACE) digital diagnostic tool, https://pacev2.apexcovantage.com/. PACE helps ensure that figures meet PLOS requirements. To use PACE, you must first register as a user. Registration is free. Then, login and navigate to the UPLOAD tab, where you will find detailed instructions on how to use the tool. If you encounter any issues or have any questions when using PACE, please email PLOS at figures@plos.org. Please note that Supporting Information files do not need this step.

PONE-D-22-12508R1Immunogenicity and reactogenicity of a third dose of BNT162b2 vaccine for COVID-19 after a primary regimen with BBIBP-CorV or BNT162b2 vaccines in Lima, Peru.PLOS ONE

Dear Dr. Natalia Gladys Gladys Vargas Herrera,

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 Oct 30 2022 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 rebuttal 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,

Daniela Flavia Hozbor

Academic Editor

PLOS ONE

Journal Requirements:

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.

[Note: HTML markup is below. Please do not edit.]

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: (No Response)

Reviewer #2: All comments have been addressed

**********

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: No

Reviewer #2: Yes

**********

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

Reviewer #1: Yes

Reviewer #2: 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

Reviewer #2: Yes

**********

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

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 #1: In the revised version of their manuscript, Herrera and colleagues have adequately addressed most of my comments.

A few remaining aspects:

1)

Figure 2 legend is still missing a definition of whiskers, bars, etc.

2)

Given the differences in immunogenicity between the different vaccines, I would still consider a version of Table 3 separated by the primary vaccination regimen informative (see previous comment on “Lines 243-245/Table 3”). Such a table could go into the supplement.

3)

Lines 351-351 (and previous comment on “Lines 349-351”): While the authors have modified their statement in response to my previous comment, I still consider it misleading. The cited work by Goel has determined that the post-boost “fold-change” in neutralization titer (but not the titer itself) inversely correlated with pre-boost titers. Because the comparison of pre- and post-boost titers in this study is strongly influence by the differences in the cohorts (in terms of baseline vaccine and their typical response to mRNA vaccines – see previous comment), I would suggest removing this paragraph.

4)

Lines 84-85: The addition of the information on the time between doses is appreciated. However, it would be placed better in the results section when the two cohorts described. Moreover, differentiation by the primary vaccine type (BBIBP-CorV or BNT162b2) would be informative.

5)

Line 365: This statement could be worded a bit more careful (“may be” or “can be” “explained” rather than “is” explained).

6)

Line 385: Using the term “best” for the description of the used adjustment strategies should be avoided or explained (why are the methods used the ‘best’)?

Reviewer #2: (No Response)

**********

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: 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.]

While revising your submission, please upload your figure files to the Preflight Analysis and Conversion Engine (PACE) digital diagnostic tool, https://pacev2.apexcovantage.com/. PACE helps ensure that figures meet PLOS requirements. To use PACE, you must first register as a user. Registration is free. Then, login and navigate to the UPLOAD tab, where you will find detailed instructions on how to use the tool. If you encounter any issues or have any questions when using PACE, please email PLOS at figures@plos.org. Please note that Supporting Information files do not need this step.

Immunogenicity and reactogenicity of a third dose of BNT162b2 vaccine for COVID-19 after a primary regimen with BBIBP-CorV or BNT162b2 vaccines in Lima, Peru.

PONE-D-22-12508R2

Dear Dr. Natalia Gladys Gladys Vargas Herrera,

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 for payment will follow shortly after the formal acceptance. To ensure an efficient process, please log into Editorial Manager at http://www.editorialmanager.com/pone/, click the 'Update My Information' link at the top of the page, and double check that your user information is up-to-date. If you have any billing related questions, please contact our Author Billing department directly at authorbilling@plos.org.

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,

Daniela Flavia Hozbor

Academic Editor

PLOS ONE

Additional Editor Comments (optional):

Reviewers' comments: