Belief in Conspiracy Theories about COVID-19 Vaccines among Brazilians: A National Cross-Sectional Study

Round 1

Reviewer 1 Report

The topic seemed topical and exciting.

I have a few reservations about the paper:

1.      Authors must provide an evaluation comparing the different demographic variables (such as Age group, Civil status, and Gender) and the variables.

In the current format, it is challenging to understand how the basic human features are influencing their intention or belief.

2.      Authors should provide a section “Theoretical and Practical Implication” separately.

The authors explain how the outcomes of the current study help to prepare for the future in terms of policy-making and academic research.

3.      There are some discrepancies between the “Aim” and “Outcome” of the study.

The authors must rewrite the Aim of the Study in a better way in Lines 118-120.

4.      Authors should provide a section “Limitation and Future Research” separately.

5.      In Line 155, "I do not trust vaccines from 'ideological countries'…Russia, or Cuba";

What is the meaning of “Ideological countries”?

The authors must explain in detail.

6.      Literature Review is a section from which readers can better understand what has already been done in the area. Currently, I don’t find a Literature Review Section. So, the Authors should include a section called “Literature Review.”

7.      All the responses are collected from the same source.

The authors provide a Table or explanation of How the Common Method Bias (CMB) is controlled.

8.      In Table 1 Teve acesso restrito a Essentials supplies…pandemia de covid-19

Some items are written in English, and some are written in another language.

Generally, the readers of the paper are from all over the world.

So, the authors must provide a common language, such as English, to understand everyone easily.

  1. There are some discrepancies between the “Aim” and “Outcome” of the study.

The authors must rewrite the Aim of the Study in a better way in Lines 118-120.

2.      In Line 155, "I do not trust vaccines from 'ideological countries'…Russia, or Cuba";

What is the meaning of “Ideological countries”?

The authors must explain in detail.

3.      All the responses are collected from the same source.

The authors provide a Table or explanation of How the Common Method Bias (CMB) is controlled.

4.      In Table 1 Teve acesso restrito a Essentials supplies…pandemia de covid-19

Some items are written in English, and some are written in another language.

Generally, the readers of the paper are from all over the world.

So, the authors must provide a common language, such as English, to understand everyone easily.

Author Response

Dear Reviewers,

We appreciate the valuable comments and suggestions provided, which have significantly enhanced the manuscript. Below, we detail how each request was addressed in the revised version of the article:

1. Demographic Variables Assessment: In the "Results" section, we improved the description of the results by including how demographic variables relate to beliefs in conspiracy theories.

2. Theoretical and Practical Implications Section: We added a separate section detailing how the study's results help prepare for the future in terms of policy-making and academic research. This section emphasizes the need for evidence-based strategies to combat misinformation and promote media literacy.

3. Clarification of Study Objective: We rewrote the study's objective to more clearly reflect the intentions and scope of the research, aligning them with the presented results. This revision is now clearly outlined in lines 118-120 of the manuscript.

4. Limitations and Future Research Section: We included a dedicated section that discusses the study's limitations and suggests directions for future research. This section also addresses the need to consider additional variables, such as the mental health of the participants.

5. Explanation of "Ideological Countries": We expanded the discussion on what "ideological countries" mean in the results section, explaining that the term refers to nations with governments heavily influenced by specific ideologies, such as communism or socialism, which can affect public perception of the credibility of vaccines from these countries.

6. Literature Review Section: We incorporated a robust literature review section that contextualizes the study within the existing literature on vaccine hesitancy and conspiracy theories, highlighting what has been explored and where our study adds new insights.

7. Common Method Bias (CMB) Control: We provided a detailed explanation of how common method bias was recognized and controlled, ensuring the reliability of the data collected via online questionnaires.

8. Consistency in Table Language: We ensured that Table 1 and all other tables in the study now consistently use English, to ensure that readers around the world can easily understand the content presented.

We hope that the changes and additions made meet the review committee's satisfaction and contribute to the clarity and impact of the study. We thank you again for the constructive suggestions and are open to further feedback.

Reviewer 2 Report

I appreciate the opportunity of being able to review this interesting paper aimed to provide information regarding conspiracy theories about COVID-19 vaccines in Brazilian population. Its results are interesting and useful to different countries, since conspiracy theories are being observed worldwide.

My only major concern relates to the selection bias, since participants were mainly women, with high educational level, although the intention was to have a representative population of Brazilian.

1.     Considering that the survey was conducted between May and August 2020 and that this article will be read some years after the pandemic is over, it will be convenient to emphasize that at that time there were no vaccines available and/or if there were some vaccine clinical trials being carried out in the country. Public opinion regarding vaccines might be influenced by the local circumstances at the moment the poll was carried out.

2.     Lines 207-208: It reads “The study was conducted following the ethical research rules of the two participating countries”. Can you please clarify, considering that the survey was carried out only in Brazil?

3.     The participants were mainly women (75%); with higher education (81%) and with more than six rooms in their households (56%). These results cannot be considered as representative of Brazilian population. Considering how participants were recruited (snowball sampling procedure), with the explicit request to the “seeds” to recruit other individuals from the same category through their digital social networks, it seems that this strategy did not work out. Although the authors recognize this limitation (see lines 328-332), the fact that the participants were not actually representative of Brazilian population, due to the “digital selection bias”; implies that it is better not to refer to them as “representative”. The digital selection bias explains that they were of higher education, but not the gender gap.  

4.     The way data are presented in the text contributes to confusion. An example is this paragraph (lines 223-226): knowing someone who had COVID-19 (2,444; 57.5%), and not knowing anyone who had died from COVID-19 (3,586; 225 84.4%). It is easier “knowing someone who had COVID-19 (2,444; 57.5%), and had died from COVID-19 (xxx; 15.4%). Particularly since in the Table, data was presented as “Knowing someone who has died by covid-19”

5.     Table 1. I have several comments regarding this Table.

a.     Some of the headings have this: [ref]. What does it mean? Please clarify.

b.     Regarding the p value between civil status: does it mean that more not-single believe in conspiracy theory? (difference between 29.8 vs 23.9%, p < 0.001). Is this correct?

c.     There are some phrases that are written in Portuguese. Please translate (ie “conteudo de desinformacao about covid-19”). There are many more examples like this one.

6.     Table 2. There are some sentences in Portuguese.

7.     Line 259: considering the characteristics of the participants, I think that the population is not “a representative sample” of Brazilian population.

8.     Lines 342-344: it is not clear what indeed aligns with initiatives aimed at achieving the Sustainable Development Goals; is the gender gap?

9.     Lines 446-447: It reads “Informed consent has been obtained online from all the participants to publish this paper”. This sentence needs clarification: did participants consent to participate in the study or, after the study was finished, they consented to the publication? It will be rather strange to have the consent for publication rather than to participate.

Author Response

Dear Reviewers,

Thank you for your detailed feedback and valuable insights. We have carefully considered each point and made the necessary revisions to the manuscript. Below, we outline how each of the reviewers' requests has been addressed in this revised version:

1. Context of Vaccine Availability: We have emphasized the context of vaccine availability during May and August 2020, noting that there were no vaccines available and highlighting any clinical trials ongoing at that time. This has been clearly stated to reflect the influence of local circumstances on public opinion during the survey period.

2. Ethical Research Rules Clarification: We corrected the statement to specify that the study followed ethical research guidelines applicable within Brazil, as the survey was conducted solely in this country.

3. Representativeness of the Sample: We have revised the text to avoid referring to the sample as "representative" of the Brazilian population. We acknowledge the "digital selection bias" and the specifics of the recruitment strategy, which likely influenced the demographic composition of our sample. This adjustment better reflects the nature of the sample and addresses the overrepresentation of certain demographics.

4. Presentation of Data in Text: We have clarified the presentation of data concerning those who knew someone who had COVID-19 and those who had died from the disease, making it consistent with the data presented in the tables.

5. Clarifications in Table 1:

   - [ref] in Headings: We have clearaed and informative.

   - p-value Interpretation: We have clarified that the difference in belief in conspiracy theories between not-single and single respondents is statistically significant, and we provided a more detailed explanation of how civil status influences belief prevalence.

   - Translation Issues: All non-English terms and phrases have been translated into English to maintain consistency and ensure understandability for an international audience.

6. Language Consistency in Table 2: We have ensured that all text in Table 2 is in English, removing any Portuguese sentences to maintain the uniformity of the manuscript.

7. Sample Representativeness: Following your suggestion, we have revised line 259 to clarify that the sample does not represent the Brazilian population due to the biases discussed earlier.

8. Clarification on Sustainable Development Goals: We have specified which initiatives align with the Sustainable Development Goals, particularly in relation to health equity and gender disparities in health access.

9. Informed Consent Clarification: We have clarified the informed consent process. It is specified that consent was obtained for participation in the study, and separately, consent was also obtained for the publication of the findings.

We hope that these revisions adequately address the concerns raised and improve the clarity and impact of our study. We are grateful for the opportunity to refine our work and welcome any further suggestions you might have.

Best regards,