Social and Structural Determinants of Health Associated with COVID-19 Vaccine Hesitancy among Older Adults in the United States

Abstract

State-level COVID-19 vaccination rates among older adults have been uneven in the United States. Due to the immunocompromised nature of older adults, vaccine hesitancy increases the risk of morbidity and mortality. This study aims to determine the association between the social determinants of health, the structural determinants of health, and COVID-19 vaccine hesitancy among older adults in the United States. Secondary data from the Health and Retirement Study (HRS) dataset were used. A descriptive analysis and multinomial multivariable logistic regression were performed to examine the association of the independent variables—gender, age, race, immigration status, marital status, broadband internet access, social security income, Medicare coverage, education, and frequency of religious service—with the dependent variable, vaccine hesitancy. Compared to the respondents with no vaccine hesitancy and without the specific predictor, the respondents who reported religious attendance at least once/week were more likely to be “somewhat hesitant”, divorced respondents had higher odds of being “somewhat hesitant”, and older adults aged 65–74 years were more likely to be “very hesitant” or “somewhat hesitant” about the COVID-19 vaccine. Compared to the respondents with no vaccine hesitancy and without the specific predictor, females had higher odds of being “very hesitant”, “somewhat hesitant”, or a “little hesitant”, and African Americans were more likely to be “very hesitant”, “somewhat hesitant”, or a “little hesitant” about the COVID-19 vaccine. Addressing these factors may limit the barriers to vaccine uptake reported among older adults and improve herd immunity among the immunocompromised population.

Full text

Citation: Kalu, K.; Shah, G.; Tung,
H.-J.; Bland, H.W. Social and
Structural Determinants of Health
Associated with COVID-19 Vaccine
Hesitancy among Older Adults in the
United States. Vaccines 2024,12, 521.
https://doi.org/10.3390/
vaccines12050521
Academic Editor: Christian Napoli
Received: 19 April 2024
Revised: 2 May 2024
Accepted: 6 May 2024
Published: 10 May 2024
Copyright: © 2024 by the authors.
Licensee MDPI, Basel, Switzerland.
This article is an open access article
distributed under the terms and
conditions of the Creative Commons
Attribution (CC BY) license (https://
creativecommons.org/licenses/by/
4.0/).
Article
Social and Structural Determinants of Health Associated with
COVID-19 Vaccine Hesitancy among Older Adults in the
United States
Kingsley Kalu , Gulzar Shah * , Ho-Jui Tung and Helen W. Bland
Jian-Ping Hsu College of Public Health, Georgia Southern University, Statesboro, GA 30458, USA;
kk13870@georgiasouthern.edu (K.K.); htung@georgiasouthern.edu (H.-J.T.);
hwbland@georgiasouthern.edu (H.W.B.)
*Correspondence: gshah@georgiasouthern.edu; Tel.: +1-912-478-2419
Abstract: State-level COVID-19 vaccination rates among older adults have been uneven in the United
States. Due to the immunocompromised nature of older adults, vaccine hesitancy increases the risk of
morbidity and mortality. This study aims to determine the association between the social determinants
of health, the structural determinants of health, and COVID-19 vaccine hesitancy among older adults
in the United States. Secondary data from the Health and Retirement Study (HRS) dataset were used.
A descriptive analysis and multinomial multivariable logistic regression were performed to examine
the association of the independent variables—gender, age, race, immigration status, marital status,
broadband internet access, social security income, Medicare coverage, education, and frequency of
religious service—with the dependent variable, vaccine hesitancy. Compared to the respondents
with no vaccine hesitancy and without the specific predictor, the respondents who reported religious
attendance at least once/week were more likely to be “somewhat hesitant”, divorced respondents had
higher odds of being “somewhat hesitant”, and older adults aged
65–74 ye
ars were more likely to be
“very hesitant” or “somewhat hesitant” about the COVID-19 vaccine. Compared to the respondents
with no vaccine hesitancy and without the specific predictor, females had higher odds of being “very
hesitant”, “somewhat hesitant”, or a “little hesitant”, and African Americans were more likely to be
“very hesitant”, “somewhat hesitant”, or a “little hesitant” about the COVID-19 vaccine. Addressing
these factors may limit the barriers to vaccine uptake reported among older adults and improve herd
immunity among the immunocompromised population.
Keywords: vaccine hesitancy; immunocompromised nature; social determinants of health; structural
determinants of health; religion; vaccine-preventable disease; older adults
1. Introduction
Vaccination is considered the most significant achievement in public health since
the dawn of the 18th century because it has significantly contributed to the reduction in
vaccine-preventable infectious diseases [
1
,
2
]. From the discovery of smallpox vaccination
to the present, a growing proportion of people has shown reluctance towards vaccinations,
leading to numerous anti-vaccine campaigns and activities [3–5].
Vaccine hesitancy is a set of beliefs and behaviors exhibited to reject vaccination
despite vaccine availability [
6
,
7
]. The Sage Working Group (WG) on vaccine hesitancy
defined vaccine hesitancy “as the delay in acceptance or refusal of vaccination despite the
availability of vaccination services”. “Vaccine hesitancy is complex and context-specific,
varying across time, place, and vaccines, which is influenced by factors such as complacency,
convenience, and confidence” [
8
,
9
]. Vaccine hesitancy occurs across a behavioral continuum,
because some vaccine-hesitant individuals completely accept vaccines without hesitation,
whereas others refuse them entirely without hesitation, yet others are between these two
extremes [
9
,
10
]. Thus, the hesitancy continuum is sometimes measured as refusing all
Vaccines 2024,12, 521. https://doi.org/10.3390/vaccines12050521 https://www.mdpi.com/journal/vaccines

Vaccines 2024,12, 521 2 of 14
vaccines, refusing but unsure, refusing some vaccines, delaying, accepting some, accepting
but unsure, and accepting all vaccines [9].
Vaccine hesitancy is a critical public health challenge in the fight against preventable
infectious diseases. It has been a problem for global health since the discovery of vaccina-
tion [
11
–
13
]. Vaccine hesitancy makes it difficult to achieve herd immunity, which has led
to an increased risk of mortality and morbidity in immunocompromised people, such as
pregnant women, older adults, and children within the community [
14
–
16
]. Additionally,
vaccine hesitancy can lead to increased healthcare expenditure, adverse health outcomes,
and more burden on families, the healthcare system, and the government [17,18].
As of 2021, the United States had around 55.7 million adults who were aged 65 years
or more. The majority of these older Americans were women with at least one chronic
disease [
19
]. Older adults have an increased risk of adverse health outcomes when an
infection occurs due to their limited regenerative capacity, their immunocompromised
nature, and the presence of co-morbidities [20].
During the COVID-19 pandemic in the United States, there were uneven COVID-
19 vaccination rates among older adults, with the lowest rate being in Utah (58%) [
21
].
Between 2020 and 2023, approximately 868,831 COVID-19-related deaths occurred in the
US among adults aged 65 years and older, with men accounting for 53% of the deaths [
22
].
Although there was a decline in COVID-19 mortality among older adults during the rollout
of vaccination in December 2020 in the United States, COVID-19 deaths among adults
65 years and older were reported to have increased to about 88% in September 2022 [
23
].
During the prevalence of Omicron BA.2 and Delta variants in 2022, adults aged 65 years
and above in America experienced higher COVID-19 hospitalization rates compared to
younger adults [18].
The Advisory Committee on Immunization Practices (ACIP) recommended the biva-
lent COVID-19 vaccine dose in September 2022. Despite that recommendation, 76% of US
adults aged 65 years and older who were hospitalized for COVID-19 had not received the
bivalent dose, and 16% had not received any COVID-19 vaccine [
24
]. In 2023, older adults
comprised nearly 90% of COVID-19-related deaths in the United States. They make up 63%
of all COVID-related hospitalizations, with most of them having multiple comorbidities;
only 24% had received the recommended COVID-19 bivalent vaccine [
24
,
25
]. The COVID-
19 pandemic has led to adverse health outcomes, which can cause a significant healthcare
burden [
26
]. The older adults who declined vaccination encountered increased healthcare
burden and unfavorable health outcomes, such as morbidity, increased hospitalization,
and significant COVID-19 death rates, because they tended to have immunocompromised
status and comorbidities [18,23,27].
Social determinants of health (SDoHs) are the “conditions in which people are born,
grow, work, live and the wider set of forces and systems shaping the conditions of daily
life” [
28
]. Five domains reflect the SDoHs: (a) economic, e.g., income; (b) healthcare access
and quality, and health insurance; (c) social and community context, e.g., marital status,
neighborhood; (d) built environment, e.g., internet access; and (e) education access and
quality [
29
]. Social Security income (SSI) serves as a foundation for income support and
economic security programs to ease the burden of older adults in the United States [
30
].
Although the social security income benefit program may seem insufficient, it has been
linked to socioeconomic health disparities [
31
]. Marital status as a determinant of health
has been linked to health outcomes and factors in spouses providing cognitive, social, and
emotional support and social integration within the community [
32
,
33
]. About 2
2 milli
on
American older adults (i.e., African American and Latino seniors) do not have and cannot
access broadband internet at home, which is a significant determinant of health [
34
,
35
]. In
addition, older adults without internet access lack access to healthcare and health-related
information [
34
,
36
]. Education as a determinant of health has been linked to health out-
comes, especially for older adults because it allows them to comprehend complex health
information and enhance their health literacy [
29
]. Although the COVID-19 vaccines were
freely administered regardless of insurance status in the United States [
37
], individuals

Vaccines 2024,12, 521 3 of 14
with health insurance had the opportunity to inquire about health information from their
primary healthcare provider [
38
]. It is pertinent to assess the impact of this health informa-
tion, especially among older adults with health insurance coverage, because people were
reluctant to take the COVID-19 vaccine when it became available due to the increasing
source of misinformation [39].
Structural determinants of health (StrDoHs) are cultural, political, social, and eco-
nomic structures that form the distribution of symbolic power, materials, and resources [
40
].
StrDoHs are the basis of health inequities, and they look at the interplay between socio-
political factors because they examine the quality of the social determinants of health
experienced by people in their neighborhoods and communities [
40
,
41
]. Although religion
is considered a social and structural determinant of health, the latter can influence institu-
tional and socioeconomic conditions, such as economic decisions, political parties, policy,
racism, colonialism, and admittance to electoral offices [42]. Religion has also been linked
to individual health outcomes via social support [
43
–
45
]. The five dimensions of religiosity
are personal practice, religious exclusivity, religious belief, external practice (i.e., religious
service attendance, social activities, and group membership), and religious salience [
46
].
Over 90% of American older adults consider themselves to be religious or spiritual. This
could be attributed to the fact that around 50% of them attend religious services on a weekly
basis, as well as engage in private religious practices, such as praying [
47
]. Few studies
have tried to assess various concepts of religiosity and vaccine hesitancy; a study focused
on religious identity being associated with COVID-19 vaccine intention [
48
]. Another study
revealed that religious beliefs impact scientific and medically sound evidence, leading to
vaccine hesitancy [
49
]. Martens and Rutjens (2022) showed that religiosity and spirituality
contributed to ongoing COVID-19 vaccination rates [
50
]. Another study accessed com-
mon religious beliefs associated with vaccine hesitancy and its consequences [
51
]. Only a
few studies have researched the frequency of religious service attendance and COVID-19
vaccine hesitancy in older adults in the United States.
Multiple studies have identified various factors that contribute to vaccine hesitancy.
These include ethnicity, socioeconomic status, distrust, political affiliation, misinformation,
and a culturally insensitive healthcare system as causes of vaccine hesitancy. These factors
impact health disparities and are associated with vaccine intention [52–57]. A few studies
have researched COVID-19 vaccine hesitancy and older adults using state-level data. A
study looked at the impact of health equity in COVID-19 vaccination among older adults, fo-
cusing on occupation, language, and housing [
58
]. Another study examined the association
between health information consumption, trust dynamics, and COVID-19 vaccine hesitancy
among older adults [
59
]. In addition, a study focused on the determinants of vaccine ac-
ceptability in older adults aged 50 years and older by examining human immunodeficiency
virus (HIV) disease, demographic characteristics, and psychosocial factors [
60
]. Cimone
and colleagues evaluated the association between COVID-19 vaccine intention and percep-
tion in older adults of an integrated health system during Ju
ne 2021–February 2021 [61]
.
In contrast, Sun and Rhubart focused on the association of rural-urban differences and
disability and aging services and COVID-19 vaccination rates among older adults using
county-level data [
62
]. Yet, another research study focused on the social and structural
determinants of health to investigate attitudes and knowledge toward COVID-19 vaccine
uptake among diverse racial and ethnic groups [54].
The current study is unique because it focuses on COVID-19 vaccine hesitancy among
older adults before the onset and during the COVID-19 vaccine administration, and this
aligns with the definition of vaccine hesitancy as a behavioral continuum. Limited studies
have been conducted to identify the association between each domain of the SDoHs and
vaccine hesitancy among older adults in the United States. In addition, none of the studies
used a nationally representative sample of older adults in the United States (U.S.) to
examine the association between the social and structural determinants of health and
vaccine hesitancy in older adults in the United States. Lastly, this study aimed to assess
the association between the social-structural determinants of health and vaccine hesitancy

Vaccines 2024,12, 521 4 of 14
in older adults in the United States. These explanatory variables provide a new focus
as to why vaccine hesitancy persists among older adults. The object of this study was
to determine: (a) the association between the social determinants of health and vaccine
hesitancy, and (b) the association between the structural determinants of health and vaccine
hesitancy among older adults in the United States.
2. Materials and Methods
2.1. Data Source
The research used secondary data from the Health and Retirement Study (HRS), a
nationally representative sample of the older adult population in the United States [
63
].
The National Institute on Aging (NIA), under the direction of the United States Congress,
created the Health and Retirement Study to inform discussion at a national level about
health and retirement issues among the growing population of older Americans. In 1992,
the HRS launched a longitudinal survey of American older adults with a complex panel
structure and sample design, which included information regarding successful aging (i.e.,
cognitive, public, and psychological); detailed health and economic information, behav-
ior, and choices (i.e., health behaviors, work, and residence); and events and transitions
(widowhood and institutionalization). The HRS participants represent all the United States
population aged 50 years and older and are followed to death. The HRS participants are
grouped in cohorts based on the year of birth. Every two years, new cohorts of participants
are added, and the samples are refreshed with younger cohorts every six years. Although
the HRS sample size ranges from 18,000 to 23,000 in any given wave [
64
–
66
], the sample
size for this study was N= 2311. This was based on the dependent variable of interest and
restricted to participants aged 65 years and older who answered the COVID-19 vaccine
hesitancy question. The National Institute on Aging (NIA) classifies older adults in the
United States as people aged 65 years or older, and this selected age group also represents
the age of Medicare eligibility [67,68].
2.2. Sampling Design
A multi-stage probability sampling design of United States households involving
geographical stratification, clustering, and oversampling of certain demographic groups
was used for the HRS study [
59
,
69
]. This multi-stage area probability design consists of
four stage selections the primary stage selection details information regarding core samples,
Hispanic supplements, Black supplements, and Florida oversampling; the secondary stage
selection of area details information of second-stage sampling unit (SSU) stratification,
selection, and allocation; the third stage focuses on the selection of housing units-located ge-
ographical area; and the fourth stage details participant selection, in which the interviewer
made a list of all household members within each sampled housing unit [70].
2.3. Data Collection
The COVID-19-related questions were incorporated in the 2020 HRS study, and the
COVID-19 core interview data collection period was initially from March 2020 to June
2021 and repeated in 2022 [
71
]. The COVID-19 Project of the 2020 Health and Retirement
Study (HRS) was administered to the 50% random sub-sample of households initially
assigned to enhanced face-to-face interviewing (EFTF). Interviews were conducted via
the web or telephone due to restrictions concerning social distancing and social contacts.
Respondents who preferred in-person interviews were sent the self-administered leave-
behind questionnaire [
72
–
74
]. Information on the questionnaire, data collection instruments,
HRS COVID-19 data resources and release date, validation, and its application can be
found at this link: https://hrs.isr.umich.edu/data-products/covid-19 (accessed on 10
February 2024)

Vaccines 2024,12, 521 5 of 14
2.4. Variables
2.4.1. Dependent Variable
Although the data collection for the 2020 COVID-19 core Section started before the
COVID-19 vaccine was available, the survey question was later updated to cover partici-
pants who did not take the vaccine when it became available. The survey question that
operationalized vaccine hesitancy before the vaccine became available was “It’s possible
there will be a vaccine for coronavirus in the next several months; how likely would you be
to take a vaccine if it were available to you like a flu shot?” After the vaccine was made
available, the participants who answered no to the question “Vaccines for the coronavirus
have recently become available for some people. Have you received a vaccination shot
for the coronavirus?” were then asked the update question “How likely are you to take
a coronavirus vaccine when it becomes available to you?” The response categories both
before and after the vaccine remained the same: very likely, somewhat likely, not very likely,
and not at all likely. These were reverse-recoded into not at all hesitant, a little hesitant,
somewhat hesitant, and very hesitant.
2.4.2. Independent Variables
The independent variables reflecting the social determinants of health were measured
as social security income, marital status, broadband internet access, educational level,
and Medicare insurance coverage. The independent variable reflecting the structural
determinant of health was measured as religiosity (i.e., frequency of religious attendance).
Social Security income: The social security income variable was measured using the
survey question, “Do you currently receive any income from Social Security?” The response
categories were Yes or No.
Marital status: The variable “marital status” was measured using the survey question
“marital status” with the response categories of married, separated/divorced, widowed,
never married, and marital status unknown. The original response categories were coded
married, separated/divorced, widowed, and never married.
Internet access: The variable “Internet access” was measured using the survey ques-
tion, “Do you regularly use the Internet (World Wide Web) for sending and receiving e-mail
or for any other purpose, such as making purchases, searching for information, or making
travel reservations?” The response categories were Yes or No.
Education: The variable “education” was measured using the survey question “High-
est level of education?” The responses were No degree, GED, High school diploma, two-
year college degrees, four-year college degrees, Master’s degree, professional degree, and
degree unknown. The original response categories were recoded as high school diploma,
unknown degree, college degree, graduate degree, and No degree.
Health insurance: The health insurance coverage variable was measured using the
survey question, “Are you currently covered by Medicare health insurance?” The response
categories were Yes or No. Religiosity: Capturing the structural determinant of health, the
religiosity variable was measured using the survey question “How often do you attend
religious service?” and the original response categories were “more than once a week, once a
week, two or three times a month, one or more times a year, not at all”. The original responses
were at least once a week, at least once a month, at least once a year, and not at all.
2.4.3. Demographic Variables
The demographic variables of interest were age (65–74 years, 75–84 years, and 85 years
and older), gender (Female and Male), race (African American, White/Caucasian, Other),
and Immigration status (U.S.-born and Immigrant).
2.5. Analytical Methods
The data analysis consisted of descriptive and multivariable multinomial logistic
regression. A descriptive analysis, such as mean, percentages, and frequencies, was con-
ducted to describe the characteristics of the study population. A multinomial multivariable

Vaccines 2024,12, 521 6 of 14
logistic regression was conducted to examine the association of the social determinants of
health—marital status, broadband internet access, education, social security income, and
health insurance—and demographic markers—age, gender, race, and immigration status
with COVID-19 vaccine hesitancy.
Furthermore, a multinomial multivariable logistic regression was conducted to assess
the association between the structural determinants of health—frequency of religious
attendance—and demographic markers—age, gender, race, and immigration status—with
COVID-19 vaccine hesitancy. Lastly, a multinomial multivariable logistic regression was
conducted to assess the association of the social determinants of health—marital status,
broadband internet access, education, social security income, and health insurance— and
structural determinants of health—frequency of religious attendance—and demographic
markers—age, gender, race, and immigration status—with COVID-19 vaccine hesitancy.
The analysis was restricted to respondents aged 65 years and older who responded to the
vaccine hesitancy question. Based on the dataset owner’s feedback on using sampling
weights for a cross-sectional analysis, weights were not applied to the analysis. The
IBM SPSS statistical software (version 29) was used for the analysis, and the statistical
significance threshold was p≤0.05.
3. Results
3.1. Unweighted Descriptive Studies and Characteristics of the Respondents
Table 1shows the characteristics of the respondents and the descriptive statistics of
the dependent and independent variables.
Table 1. Descriptive statistics of the study participants’ characteristics, 2020–2022.
Variables Frequency Percentages
Dependent Variable
Vaccine Intention
Not Hesitant 1142 49
Little Hesitant 590 26
Somewhat Hesitant 259 11
Very Hesitant 320 14
Independent Variables
Older Adults
65–74 years 1234 53
75–84 years 777 34
85 years and older 300 13
Immigration Status
US-born 1968 85
Immigrant 343 15
Gender
Female 1405 61
Male 906 39
Ethnicity/Race
Black 464 20
Other 198 9
White 1644 71
SDoHs
Educational Level
High School 1080 47
Unknown Degree 30 1
College Degree 484 21
Graduate Degree 256 11
No Degree 461 20

Vaccines 2024,12, 521 7 of 14
Table 1. Cont.
Variables Frequency Percentages
Marital Status
Married 1105 48
Separated/Divorce 433 19
Widowed 624 27
Never Married 139 6
Social Security Income
Yes 2080 91
No 200 9
Broadband Internet Access
Yes 1334 59
No 937 41
Medicare Health Insurance
Yes 2117 93
No 162 7
StrDoHs
Frequency of religious attendance
At least once a week 836 37
2/3 times a week 206 9
At least one/more times a month 375 17
Not at all 837 37
Abbreviations: SDoHs, Social determinants of health; StrDoHs, Structural determinants of health. Note. Total
N = 2311.
Characteristics of the Respondents
The study results (Table 1) reveal that more than half of the respondents were female
(60%), and a large percentage identified their race as White (71%). The majority of the
respondents were born in the United States (85%). The respondents within the 65–74 years
age group were at least 53%, the 75–84 years age group was 34%, and the 85 years and older
age group corresponded to 13% of the respondents. The married respondents were 48%,
and 27% of the respondents were widowed. Forty-six percent of respondents had at least a
high school degree. Thirty-seven percent of the respondents reported religious attendance
at least once a week, and the same percentage reported no religious attendance. Close to
49% of the respondents were not hesitant to take the COVID-19 vaccine when available,
and 26% were a little hesitant. And many respondents had Medicare coverage (93%) and
social security income (91%).
Table 2shows that, when compared to the respondents who were 85 years and older,
those in the age group 65–74 years had higher odds of being “very hesitant” (AOR = 1.76,
CI = 1.12–2.77) about the COVID-19 vaccine or “somewhat hesitant” (AOR = 2.04, CI = 1.19–
3.49), rather than not being vaccine-hesitant. Compared to men, women were more likely
to be “very hesitant” (AOR = 1.90, CI = 1.42–2.55) about the COVID-19 vaccine, “somewhat
hesitant” (AOR = 1.95, CI = 1.42–2.67), or a “little hesitant” (AOR = 1.69, CI = 1.35–2.12),
rather than not being vaccine-hesitant. Compared to White individuals, African Americans
had higher odds of being “very hesitant” (AOR = 2.54, CI = 1.83–3.52) about the COVID-19
vaccine, “somewhat hesitant” (AOR = 2.36, CI = 1.66–3.36), or a “little hesitant” (AOR = 1.89,
CI = 1.42–2.50) rather than not being vaccine-hesitant. Compared to the respondents who
reported no religious attendance, the respondents who reported religious attendance at
least once a week were more likely to be “somewhat hesitant” (AOR = 1.82, CI = 1.30–2.56)
about the COVID-19 vaccine rather than not being vaccine-hesitant. Compared to the
respondents with no degree, high school respondents had lower odds of being a “little
hesitant” (AOR = 0.70, CI = 0.52–0.95) about the COVID-19 vaccine, and college degree
respondents had lower odds of being a “little hesitant” (AOR = 0.60, CI = 0.42–0.85).
Graduate respondents had lower odds of being “very hesitant” (AOR = 0.39, CI = 0.21–0.72)
about the COVID-19 vaccine, “somewhat hesitant” (AOR = 0.38, CI = 0.20–0.72), or a “little

Vaccines 2024,12, 521 8 of 14
hesitant” (AOR = 0.49, CI = 0.32–0.76) rather than being “very hesitant”. Compared to
the unmarried respondents, the separated/divorced respondents were more likely to be
“somewhat hesitant” (AOR = 2.32, CI = 1.15–4.68) about the COVID-19 vaccine rather than
not being vaccine-hesitant. However, there was no association between social security
income, immigration status, broadband internet use, Medicare coverage, and COVID-19
vaccine hesitancy among older adults.
Table 2. Multinomial multivariable logistic regression model showing the association between the
socio-structural and demographic determinants of health and COVID-19 vaccine hesitancy among
older adults.
Very Hesitant Somewhat Hesitant Little Hesitant
95% CI 95% CI 95% CI
AOR UL LL Sig AOR UL LL Sig AOR UL LL Sig
Marital Status
Never Married (Ref. Category) (Ref. Category) (Ref. Category)
Married 0.99 0.57 1.72 0.96 1.52 0.77 3.00 0.22 1.20 0.76 1.89 0.43
Separated/divorced 1.34 0.74 2.40 0.34 2.32 1.15 4.68 0.02 1.06 0.65 1.75 0.81
Widowed 1.30 0.73 2.31 0.38 1.47 0.73 3.00 0.28 1.02 0.63 1.65 0.95
Immigration Status
Immigrant (Ref. Category) (Ref. Category) (Ref. Category)
US-born 1.13 0.75 1.72 0.56 1.13 0.71 1.80 0.60 1.21 0.86 1.71 0.27
Educational Level
No degree (Ref. Category) (Ref. Category) (Ref. Category)
High school 0.91 0.63 1.31 0.61 0.75 0.50 1.13 0.18 0.70 0.52 0.95 0.02
Unknown degree 1.44 0.53 3.92 0.48 0.62 0.16 2.33 0.48 0.48 0.16 1.40 0.18
College 0.65 0.41 1.02 0.06 0.73 0.45 1.17 0.19 0.60 0.42 0.85 0.005
Graduate 0.39 0.21 0.72 0.003 0.38 0.20 0.72 0.003 0.49 0.32 0.76 0.001
Social Security Benefits
No social security income (Ref. Category) (Ref. Category) (Ref. Category)
Social security income 1.09 0.65 1.82 0.75 0.94 0.54 1.62 0.82 0.89 0.60 1.34 0.58
Health Insurance
No medical health insurance
(Ref. Category) (Ref. Category) (Ref. Category)
Presence of health insurance 0.91 0.53 1.56 0.72 1.43 0.75 2.72 0.28 1.25 0.78 2.00 0.36
Broadband Internet Use
No internet use (Ref. Category) (Ref. Category) (Ref. Category)
Internet use 0.76 0.56 1.03 0.08 1.11 0.79 1.55 0.56 1.02 0.80 1.31 0.87
Religiosity
Frequency of religious
attendance (Ref. Category) (Ref. Category) (Ref. Category)
At least once a week 1.29 0.95 1.75 0.10 1.82 1.30 2.56
<0.001
1.27 0.99 1.63 0.06
2/3 times a month 0.77 0.47 1.28 0.32 0.84 0.47 1.50 0.55 1.25 0.86 1.82 0.23
At least one/more times a
month 0.79 0.53 1.20 0.27 1.18 0.77 1.82 0.46 0.99 0.73 1.35 0.95
Age 85 years and older (Ref. Category) (Ref. Category) (Ref. Category)
65–74 years 1.76 1.12 2.77 0.02 2.04 1.19 3.49 0.01 1.34 0.93 1.93 0.11
75–84 years 0.89 0.57 1.40 0.62 1.26 0.73 2.15 0.41 1.12 0.79 1.59 0.53
Gender Male (Ref. Category) (Ref. Category) (Ref. Category)
Female 1.90 1.42 2.55
<0.001
1.95 1.42 2.67
<0.001
1.69 1.35 2.12
<0.001
Race White (Ref. Category) (Ref. Category) (Ref. Category)
Black 2.54 1.83 3.53
<0.001
2.36 1.66 3.36
<0.001
1.89 1.42 2.50
<0.001
Other 1.26 0.76 2.07 0.37 1.09 0.62 1.91 0.78 0.80 0.52 1.24 0.32
The reference outcome category is Not Hesitant
Note. AOR, Adjusted odds ratio; CI, Confidence interval; Ref. Category, Reference category; LL, Lower limit; UL,
Upper limit; Sig, Significant level at p≤0.05.

Vaccines 2024,12, 521 9 of 14
4. Discussion
This study provides new findings that suggest that the frequency of religious atten-
dance, marital status, and being 65–74 years old are associated with COVID-19 vaccine
hesitancy in the United States. The authors found that increased frequencies of religious
attendance were associated with higher odds of being vaccine-hesitant. Religiosity can
significantly impact vaccine hesitancy because of a complex web of intertwined mediators
and moderators between these two phenomena. For instance, religious groups differ in
their beliefs concerning the relative role of science versus divinity in the prevention and
cure of disease [
75
], which can result in variation in vaccine desirability and acceptability,
as evident from religion-based vaccine exemptions [
76
]. People with different religious
beliefs also vary in their contribution and receptivity to misinformation about the vaccines’
safety as well as their trust in medical professionals’ advice compared to such advice from
their religious leaders [77].
Numerous studies have examined various forms of religiosity (e.g., the role of religios-
ity and prayer frequency) and their impact on vaccine hesitancy [
49
,
51
]. In the regression
model that combined both the SDoH and StrDoH variables, the severity of hesitancy asso-
ciated with religiosity reduced with participants who attended religious activity at least
once a week having an almost two-fold increase in the odds of being somewhat hesitant
about the COVID-19 vaccine. This level of association seen in the StrDoHs may be related
to the refusal to validate governmental regulations, such as social distancing and insti-
tutional conflicts between religion, political affiliation, and science, especially regarding
vaccination [
78
,
79
]. The variation of hesitancy may also be related to policies intervening on
specific social determinants of health predictors and having influence mediated by existing
religious practices, norms, and culture [
40
,
44
]. Public health organizations can partner with
faith-based organizations to conduct health programs and use their “voice” to promote
vaccine acceptance.
Also, the odds of vaccine hesitancy were higher for those with a marital status of
separation and aged from 65 to 74 years.
This study showed that separated/divorced respondents among older adults were
two times more likely to be “somewhat hesitant” about the COVID-19 vaccine. This
could be due to a variety of factors, including emotional stress, changes in social support
networks, or differences in health behavior following a separation or divorce. For divorced
or separated individuals, the lack of a partner may result in less encouragement or support
for vaccination, leading to higher rates of hesitancy [
32
,
33
]. In contrast, other studies
showed no association between marital status and COVID-19 vaccine hesitancy [
80
]. This
suggests the importance of social support and social ties and how they impact health
behavior [
81
]. Groups targeted at separated or divorced people can be organized to provide
social support and health information to the members.
The findings that older adults are hesitant to use the COVID-19 vaccine were consistent
with previous studies [
39
,
82
]. However, it showed that older adults aged 65–74 years were
about two times more likely to be “very hesitant” and “somewhat hesitant”. This could be
due to a history of previous hesitancy, distrust in government, misinformation, and vaccine
brands influencing vaccine intentions during the pandemic [
59
,
83
–
85
]. The results may
suggest a worsening case of vaccine hesitancy since one would expect that age group to
be more receptive than older adults. There is a need to explore how this misinformation
and perception can be corrected. This study found that a higher level of education was
negatively associated with vaccine hesitancy among older adults in the United States. The
findings are consistent with other studies that found older respondents with a high school
degree and above had higher odds of being COVID-19 vaccine-hesitant [
86
,
87
]. However,
this study showed that older respondents with a high school degree were associated with
being a little hesitant, college degree holders were associated with being very hesitant
or little hesitant, and graduate degree holders were associated with being very hesitant,
somewhat hesitant, and a little hesitant about the COVID-19 vaccine. This suggests that
informed respondents were more knowledgeable about their health and willing to adopt

Vaccines 2024,12, 521 10 of 14
preventive health services [
86
,
88
]. Policies that encourage access to quality education must
be encouraged, and barriers to increasing levels of education must be eliminated.
The authors found no association between Medicare coverage and COVID-19 vaccine
hesitancy. This is consistent with research evidence that health insurance coverage did not
influence vaccine intention due to the freely administered COVID-19 vaccination [
89
]. The
research study also found no association between social security income and COVID-19
vaccine hesitancy, and this may suggest that it does not influence vaccine decision-making
in older adults, even though social security income could improve health outcomes and
well-being [
90
]. Although past studies showed that access to broadband internet impacted
vaccine intention [
8
,
91
], this study found no association between internet access and COVID-
19 vaccine hesitancy among older adults. The current study also found no association
between immigrant status and COVID-19 vaccine hesitancy, showing an assimilation with
the native population concerning vaccine acceptance.
The results show higher odds of vaccine hesitancy among females and African Ameri-
cans. Although this study is consistent with previous studies suggesting increased vaccine
hesitancy among women than men [
92
,
93
], this study found that older female respondents
had a two-fold increase in hesitation about the COVID-19 vaccine. The fear of possible
vaccine side effects, especially since more women are their family’s caregivers, may sug-
gest their level of hesitancy [
94
]. Women ambassadors can be empowered with health
information to take it to their families and communities. The results of this research study
agree with those of other studies that showed African Americans were more likely to be
vaccine-hesitant [
80
]. However, this study showed that African Americans had about a
three-fold increase in being “very hesitant” about the COVID-19 vaccine and a two-fold
increase in being “somewhat hesitant” or a “little hesitant”. This suggests a long history of
hesitancy toward vaccination, racism, healthcare, and biomedical mistrust [
80
,
95
]. Despite
past efforts to gain the trust of African Americans in the health system, it appears that
not much progress has been made. Public health stakeholders need to engage African
American influencers who can help to advocate the benefits of vaccination. Engaging
this racial group through community-based participatory research may help to increase
confidence since they are part of the process from vaccine development to roll-out.
This study’s findings should be viewed in the context of its limitations. First, due to
the study design, our study cannot establish causality between the variables of interest.
Also, the use of secondary data limits the variables available for analysis. For instance,
only one dimension of religiosity (i.e., frequency of religious attendance) for the structural
determinants of health was considered. This study had smaller analytic samples of the
2020 COVID-19 HRS data than full samples of HRS, which created a potential for selection
bias due to the number of missing variables. The study findings are still reasonably robust
and highly useful, given its strength of using a nationally representative dataset to analyze
the association between the variables of interest. This study contributes to a critical body of
knowledge to support health equity-related public health practice and policy initiatives on
vaccine hesitancy as it focuses on older adults, often a forgotten vulnerable population.
5. Conclusions
Our study found that social and structural determinants of health were associated with
vaccine hesitancy among older adults in the United States. Addressing social and structural
determinants of vaccine hesitancy upstream will reduce the downstream disparities in
vaccine uptake. Vaccine acceptance will improve herd immunity, mainly benefiting the
immunocompromised population. This study provides valuable quantitative empirical
evidence to guide policy and public health practice addressing vaccine hesitancy. Future
studies conducting qualitative research on vaccine hesitancy will provide additional in-
sights into and context for interventions and initiatives vested in improving vac
cine upt
ake.
Author Contributions: Conceptualization, K.K.; methodology, K.K. and G.S.; formal analysis, K.K.;
writing—original draft preparation, K.K.; writing—review and editing, K.K, G.S., H.-J.T. and H.W.B.;
supervision, G.S. All authors have read and agreed to the published version of the manuscript.

Vaccines 2024,12, 521 11 of 14
Funding: This research received no external funding.
Institutional Review Board Statement: The Georgia Southern University Institutional Review Board
approved the study under Protocol H24167 on 7 February 2024.
Informed Consent Statement: Patient consent was waived due to the use of secondary data.
Data Availability Statement: The dataset is publicly available at https://hrs.isr.umich.edu/data-
products (accessed on 10 February 2024).
Conflicts of Interest: The authors declare no conflicts of interest.
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