Demographic Differences in Compliance with COVID-19 Vaccination Timing and Completion Guidelines in the United States

Round 1

Reviewer 1 Report

The issue was analyzed many times but the problem remined. If you will continue the topic of presented paper please pay attention how to persuade people to be vaccinated. Interesting paper.

Author Response

We appreciate the reviewer's comments and have revamped the discussion in response to other reviewers' comments as well. For example, our conclusion now reads:

 

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The study examined the variance of COVID-19 vaccination compliance in US adults in August 2022 by demographic characteristics. We found that race/ethnicity, religion, and political affiliation are highly associated with vaccination compliance. Non-religion, non-democrats and NH black Americans have relatively low vaccine adherence. In order to decrease these demographic disparities and enhance people's awareness of public health, government need to establish a positive image by releasing impartial messages through the media. For public health professionals, it is important to recognize vaccine hesitancy and conduct effective vaccination interventions regarding low vaccination compliance groups."

Reviewer 2 Report

Attached file.

Comments for author File: Comments.pdf

Author Response

Reviewer 1

 

General comments.

Vaccine hesitancy is a well-known and extensively studied public health problem. The same can be said about Covid-19 vaccination. However, additional knowledge about demographic, social, and political characteristics could be useful to better understand this problem. Still, it would be helpful if the authors could stress the novelty of the study in the introductory part.

 

Authors’ response: We appreciate the reviewer comments. We have added the following into the introduction (line 92):

 

“Vaccine uptake has stalled in the United States. In light of continued challenges in increasing vaccine uptake, it is important to have a more in depth analysis of the trajectory of vaccine coverage and what differences exist across various sociodemographic groups.”

 

 

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The study has an ambitious aim to characterise all of the adult population in the US with

respect to vaccine hesitancy. For this aim and the number of independent variables the

sample size is relatively small. The results in a very scarce absolute numbers in cells

sometimes leading to 0. Moreover, the US CDC data are telling about big differences

depending on the US State, and the used sample is not allowing one to cover all the states in a representative way. The other sample problem is a non-probability (quota) principle; this is increasing probability the selection bias, which is becoming particularly important for small absolute numbers.

 

Authors’ response: The reviewer brings up excellent points. We’ve added the following to the limitations (line 354):

 

“There are limitations since this survey was conducted online using a convenience sample. Even though there are important regional differences in pandemic policies and epidemiological burden by state, we were unable to examine state-specific differences given the smaller sample size. Even though we removed respondents who completed the survey in a short amount of time, there is still a possibility that some respondents who were less honest or focused than others were included in the analysis.

 

To confirm and corroborate the findings of this research, particularly given small cell sizes, further cross-sectional or longitudinal studies are needed.”

 

 

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The title (and the following text) of the article is about the adherence to vaccination, which should be distinguished from the compliance. Adherence includes not only following an advice, but attitudes as well. There is no information that attitudes are included in this survey. Therefore, the term compliance would be more appropriate.

 

 

Authors’ response: We’ve changed the wording to “compliance” throughout the manuscript, except in a few situations where we cite others’ work.

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Also, the aim of the study (line No 94): “By examining these differences, we can identify the reasons why vaccination rates are not meeting expectations.”, considering of the variables used is an oversimplification, but still with some limited practical usefulness (see https://www.tandfonline.com/doi/full/10.4161/hv.24657).

 

 

Authors’ response: We appreciate the link to the previous study. We have modified a sentence in the introduction to read:

 

(Line 97): “Previous literature has explained the significant role of historical, political and socio-cultural context in individual decision-making about vaccination, so it is necessary for us to identify the population characterizes of low vaccine adherence by examining these differences. [17]”

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Special comments and questions.

1. The section 'Introduction':
2. Line 49: reference to these 'several studies'?

 

 

Authors’ response: We have added in the citations [7-9] to the end of this sentence.

 

7. Rosenberg, E. S.; Dorabawila, V.; Easton, D.; Bauer, U. E.; Kumar, J.; Hoen, R.; Hoefer, D.; Wu, M.; Lutterloh, E.; Conroy, M. B.; Greene, D.; Zucker, H. A. Covid-19 vaccine effectiveness in New York State. New England Journal of Medicine 2022, 386, 116–127.
8. Mizrahi, B.; Lotan, R.; Kalkstein, N.; Peretz, A.; Perez, G.; Ben-Tov, A.; Chodick, G.; Gazit, S.; Patalon, T. Correlation of SARS-COV-2-breakthrough infections to time-from-vaccine. Nature Communications 2021, 12.
9. Rzymski, P.; Camargo, C. A.; Fal, A.; Flisiak, R.; Gwenzi, W.; Kelishadi, R.; Leemans, A.; Nieto, J. J.; Ozen, A.; Perc, M.; Poniedziałek, B.; Sedikides, C.; Sellke, F.; Skirmuntt, E. C.; Stashchak, A.; Rezaei, N. Covid-19 Vaccine Boosters: The good, the bad, and the ugly. Vaccines 2021, 9, 1299.

 

 

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1. Line 55: “increased risk” of infection or hospitalisation?

 

 

Authors’ response: We clarified the sentence:

 

“..., the increased risk for infection was 2.26-fold”

 

 

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1. Line 91: the mentioned article was not analysing 'interaction' (effect

modification) and the presented article is not as well.

 

 

Authors’ response: We appreciate the correction. We have removed interaction in this sentence. Now it reads (line 91): “The research findings suggest that both race/ethnicity and religion should be taken into consideration…”

 

 

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2. The section 'Materials and methods':
3. General: was there a sample size power calculation?

 

 

Authors’ response: We added the following details into the methods (line 127): “Our sample size calculation was based on an aim for a previous project – to precisely estimate the proportion of individuals vaccinated at a given time; with a sample size of 800, we could estimate an outcome proportion of 50% (a statistically conservative estimate), based on a margin of error of 4%, an alpha of 0.05, and a power of 80%.”

 

 

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1. Line 108: age group '45 and up': Is there homogeneity in this group with

regard to associations (doubtfully)?

 

 

Authors’ response: We agree that there is heterogeneity – particularly in terms of vaccination policies early in the pandemic and perceptions of risk. However, we wanted to focus our discussion on race, religion, and politics, and age is not a main variable of interest, but a covariate to use to adjust for confounding.

 

 

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1. Line 109: not exactly clear is weighting related to sampling procedure or

statistical weighting of the final sample (in health studies weighting for

nonresponders usually introduces selection bias).

 

 

Authors’ response: Thank you for bringing up this point of clarification. It is the former, and we have edited the methods to be (line 122):

 

“We created sample weights so that our study population reflected national estimates from the US Census in terms of age, gender, region of the country, education, and race/ethnicity.”

 

 

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1. General: Regarding the dependent variable 'adherence': Is there no

possibility of collider bias as this variable is made up of two variables

with the same independent variables (could be opposite associations),

and the latter is related to the same variables again?

 

 

Authors’ response: We have thought about this, but in general the associations are similar, and we report the descriptives for timing and completion in Tables 1 and 2.

 

 

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1. General: Was the information obtained through interviews, selfaddressed questionnaires or a combination?

 

 

Authors’ response: We added in this information (line 119):

 

“Participants filled out the survey themselves online”

 

 

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1. General: were there any validation measures for the questionnaire?

 

 

Authors’ response: We added in the following (line 136):

 

“The vaccine questions were based off of the Kaiser Family Foundation COVID-19 Vaccine Monitor”

 

 

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3. The section 'Results':
4. Line 198: It would be inappropriate to compare proportions of early and

late compliers from the cross-sectional data: 'Early' persons diminished the population of 'late' compliers and this is the reason for 'fewer

started in late 2021' (line 199). Instead, rates of vaccinated in eligible

populations can be compared (time depending survival analysis): not

possible from cross-sectional data.

 

 

Authors’ response:  We agree that there are some limitations to the use of cross-sectional data. (We had already written in methods – line 367: “To confirm and corroborate the findings of this research, particularly given small cell sizes, further cross-sectional or longitudinal studies are needed.”).

 

At the same time, our goal, is to partition the population into those who were vaccinated earlier or later. Our categories are from the overall population, and we do not display information on rate or hazard ratios – for the issues that the reviewer brings up.   

 

 

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1. Line 232: if the odds is lower compared to the reference group, then the

odds ratio is higher than 1. The author probably is talking about a lower

odds ratio and not odds. However, conclusions are then going in the

opposite direction.

 

 

Authors’ response: The example on line 232 was comparing the odds of vaccination compliance in non-Hispanic Black vs non-Hispanic white participants. The odds ratio was 0.3. We have made some edits to this sentence based on other comments from reviewers, but overall believe that our interpretation is in line with recommendations from others (e.g., https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2938757/, https://www.cdc.gov/training/SIC_CaseStudy/Interpreting_Odds_ptversion.pdf although this explains interpretation exposure odds ratios and not disease odds ratios, but math is the same).

 

Line 253: “. By race/ethnicity, NH Black Americans had lower odds of medium (OR: 0.3, 95% CI: 0.1, 0.9) or high (OR: 0.2, 95% CI: 0.1, 0.5) compliance with COVID vaccination guidelines compared to NH White Americans.”

 

 

 

 

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1. Line 221 (table 3): not clear are all the variables presented in the table

mutually adjusted (included in the model)?

 

 

Authors’ response: Correct, they are adjusted. We clarified this in the table title:

 

“Table 3. Adherence to COVID-19 vaccination guidelines in multinomial, multivariable logistic regression models, United States, August 2022.”

 

And in line 235: “In a model adjusted for all shown variables, …”

 

 

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4. The section 'Discussion':
5. Line 248: Not clear statement regarding internal correlation - what

variables? Is it collinearity leading to bias? Why confounding by age, if

age is included in the adjustment model?

 

 

Authors’ response: This was a confusing sentence, and we have deleted it. We agree that we controlled for age in the model, and our study does not test for collinearity of variables.

 

 

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1. Section 'Religion': there are studies showing a positive relation of

religion to conspiracy theories

(https://doi.org/10.1093/oso/9780190844073.003.0028 ).

 

 

Authors’ response: We appreciate the reference. We added it into the discussion:

 

(Line 317): “Robertson et al. argue that religion has become a way for conspiracy theories to be normalized through their conception of shared similarities between conspiracy theories and religion (i.e., both holding beliefs in the supernatural, mysticism, prophecy, etc.) [26.]

 

The reviewer mentions a perspective that is opposite to our result.

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5. Section 'Conclusions'
6. The first sentence is not based on the empirical material of this study.

 

 

Authors’ response: We modified this sentence

 

(Line 373): “The study examined the variance of COVID-19 vaccination compliance in US adults in August 2022 by demographic characteristics. As we found that race/ethnicity, religion, and political affiliation are highly associated with vaccination compliance. Non-religion, non-democrats and NH black Americans have relatively low vaccine compliance.”

 

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1. The public health action proposal does not seem operational (diminish

racism, increase trust in government)

 

 

Authors’ response: We agree that this is aspirational and not operational. We modified the sentence to read:

 

(Line 376): “In order to decrease these demographic disparities and enhance people's awareness of public health, government need to establish a positive image by releasing impartial messages through the media.”

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1. It is not clear what is 'rationale vaccination intervention regarding

religious beliefs’ (discussion is mentioning intervention on religious

persons where adherence is better).

 

 

Authors’ response:  We edited this to be:

 

(Line 379): “For public health professionals, it is important to recognize vaccine hesitancy and conduct effective vaccination interventions regarding low vaccination compliance groups.”

 

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Reviewer 3 Report

Thank you for the opportunity to review this article, which reports the results of a cross-sectional survey conducted to investigate the demographic patterns of COVID-19 vaccination adherence.

The study is well conducted, but improvements can be made in the presentation of the results. Specifically, there is a table which seems to have been reported twice in the manuscript, first time as Table 1 and second as Table 2, please correct also in the text to refer to the right table.

Also, in my opinion the authors should state better the aims of the study at the end of the Introduction, avoiding to express preliminary hypothesis.

Author Response

Reviewer 2

 

Thank you for the opportunity to review this article, which reports the results of a cross-sectional survey conducted to investigate the demographic patterns of COVID-19 vaccination adherence.

 

The study is well conducted, but improvements can be made in the presentation of the results. Specifically, there is a table which seems to have been reported twice in the manuscript, first time as Table 1 and second as Table 2, please correct also in the text to refer to the right table.

 

 

Authors’ response: These are different tables but we have changed the captions to be more transparent:

 

Table 1. Vaccination completeness, and its distribution by demographic characteristics, race/ethnicity, religion, and political affiliation, stratified by vaccination completeness, United States, August 2022.

 

Table 2. Vaccination timing, and its distribution by demographic characteristics, race/ethnicity, religion, and political affiliation, , United States, August 2022.

 

 

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Also, in my opinion the authors should state better the aims of the study at the end of the Introduction, avoiding to express preliminary hypothesis.

 

 

Authors’ response: (Line 105): “Thus, we aim to systematically examine demographic patterns of adherence to COVID-19 vaccination and mainly explore how race/ethnicity, religion, and political affiliation impact the COVID-19 vaccination. In specific, 1) to assess the pattern in vaccination completeness, 2) to assess the pattern in timing of vaccination start, and 3) to characterize individuals by compliance with vaccination guidelines (combining completeness and time).”

 

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Round 2

Reviewer 2 Report

The manuscript has been improved and can be accepted for the publication.