How well does vaccine literacy predict intention to vaccinate and vaccination status? A systematic review and meta-analysis

Figures & data

Figure 1. PRISMA flow diagram of the review process. VL: vaccine literacy.

Table 1. Characteristics of the studies included in the systematic review.

First author, year	Country	Study design	Target population (sample size)	Vaccination	Quality
Studies investigating vaccination intention only
Alshehry, 2021	Saudi Arabia	CS	Nursing students recruited in universities (N = 1170)	SARS-CoV-2	7
Gendler, 2021 #	Israel	CS	Parents of children aged 12–15 years recruited online using social networks (N = 520)	SARS-CoV-2	5
Gusar, 2021	Croatia	CS	General population aged ≥18 years recruited online using social networks (N = 1227)	SARS-CoV-2	5
Nath, 2021	Bangladesh	CS	General population aged 18–30 years recruited online using social networks (N = 343)	SARS-CoV-2	9
Yadete, 2021 #	United States	CS	General population aged ≥18 years recruited online using commercial panels (N = 2138)	SARS-CoV-2	8
Achrekar, 2022 #	India	CS	General population aged ≥18 years recruited online using commercial panels (N = 687)	SARS-CoV-2	8
Batra, 2022 #	United States	CS	General population aged ≥18 years recruited online using commercial panels (N = 501)	SARS-CoV-2	8
Gutierrez, 2022 #	Saudi Arabia	CS	General population aged ≥18 years recruited online using social networks (N = 2514)	SARS-CoV-2	7
Suzuki, 2022	Japan	CS	University male (N = 65) and female (N = 57) students aged 18–35 years recruited in four universities using campus website/course of study e-bulletin boards	HPV	5
Studies investigating vaccination status only
Lee, 2015	United States	CS	White (N = 1929) and AAPI (N = 341) female undergraduate students aged 18–25 years recruited in a university using institutional e-mail address (N = 1929)	HPV	8
Biasio, 2020 (A)	Italy	CS	Individuals aged ≥65 years attending an appointment in a local health unit (N = 128)	IPT	7
Engelbrecht, 2022	South Africa	CS	General population ≥18 years recruited online using social networks (N = 10466)	SARS-CoV-2	7
Yilmaz, 2022 #	Turkey	CS	Nursing students recruited in a university (N = 391)	SARS-CoV-2	6
Studies investigating both vaccination intention and status
Biasio, 2020 (B) #	Italy	CS	General population including representatives of citizens, patients and healthcare workers recruited from e-mail list of a medical foundation and using social networks (N = 885)	SARS-CoV-2 - intention Influenza – intention and status	5
Krishnamurthy, 2022 #	Barbados	CS	Healthcare professionals recruited in a hospital using institutional e-mail address (N = 343)	SARS-CoV-2 - intention Influenza – status	5
Kittipimpanon, 2022	Thailand	CS	Older adults aged ≥60 years recruited online using social networks (N = 224)	SARS-CoV-2 - intention and status	7
Correa-Rodriguez, 2022 #	Spain	CS	Patients with a systemic autoimmune disease aged ≥18 years recruited from an online association using a patient association Facebook page (N = 319)	SARS-CoV-2 - intention Influenza – status	5
Li, 2022	China	CS	General population ≥18 years recruited online (N = 362)	SARS-CoV-2 - intention and status	6

AAPI: AAPI: Asian American and Pacific Islander; CS: cross-sectional; HPV: human papilloma virus; IPT: influenza, Pneumococcus & tetanus.

#:studies included in the meta-analysis.

Table 2. Association between vaccine literacy (VL) and vaccination intention.

First author, year	VL		Vaccination intention		Statistical analysis	Main findings		Adjustment factors
	Measurement, coding	Domains	Measurement	Coding		Unadjusted analysis	Adjusted analysis
SARS-CoV-2
Biasio, 2020 (B) #	Adapted version of HLVa-IT, continuous	-Functional - Interactive/critical	One question on the intention to have COVID-19 vaccination	Two categories: − yes − no	Kruskal Wallis	Non-significant association between higher functional VL and the intention to be vaccinated (p = .491); significant association between higher interactive/critical VL and the intention to be vaccinated (p < .001)	NA	NA
Alshehry, 2021	Adapted version of HLVa-IT, continuous	- Interactive/critical	One question on the intention to have COVID-19 vaccination	Three categories: − no − not sure − yes	Multinomial logistic regression	NA	Non-significant association between higher interactive/critical VL and the intention to be vaccinated (β = −0.10)	COVID-19 risk perception and attitudes to COVID-19 vaccine
Krishnamurthy, 2021 #	Ad hoc questionnaire, continuous	− Interactive/critical	One question on the intention to have COVID-19 vaccination	Two categories: − yes − later/no	Not reported	Significant association between higher interactive/critical VL and the intention to be vaccinated (p < .05)	NA	NA
Yadete, 2021 #	HLVa-IT, continuous	- Functional - Interactive - Critical	One question on the intention to have booster dose	Two categories: − yes − no	t-Test	Significant association between higher functional, interactive, and critical VL and the intention to be vaccinated (p < .001)	NA	NA
Gendler, 2021 #	COVID-19 VLS (adapted from HLVa-IT), continuous	- Overall - Functional - Interactive/critical	Two questions on the willingness to vaccinate their children against COVID-19	Two categories: − very likely or somewhat likely − somewhat unlikely or definitely not likely	t-Test	Non-significant association between higher functional, interactive/critical, and overall VL and the intention to vaccinate their children (p = .13, p = .31 and p = .06)	NA	NA
Gusar, 2021	COVID-19 VLS (adapted from HLVa-IT), continuous	- Functional - Interactive/critical	One question on the intention to have COVID-19 vaccination	Two categories: − yes − no	t-Test	Significant association between higher functional and interactive/critical and the intention to be vaccinated (both p < .01)	NA	NA
Nath, 2021	COVID-19 VLS (adapted from HLVa-IT), continuous	- Overall	One question on the intention to have COVID-19 vaccination	Level of agreement: 0 = no; 10 = yes	Multiple linear regression	Non-significant association between higher overall VL and the intention to be vaccinated (r = −0.05)	Non-significant association between higher overall VL and the intention to be vaccinated (β = −0.02)	Age, gender, COVID-19 experience, conspiracy theory believing, influence of opinion leaders
Achrekar, 2022 #	HLVa-IT, continuous	- Overall	One question on the intention to have booster dose	Two categories: − yes – no/not sure	Hierarchical multiple regression	Significant association between higher functional, interactive, critical, and overall VL and the intention to be vaccinated (p < .001)	Subgroup analysis: non-significant association between higher overall VL and the intention to be vaccinated in hesitant individuals (β = −0.011)	Age, gender, education, income, marital status, region, living condition, empowerment
Batra, 2022 #	HLVa-IT, continuous	- Overall	One question on the intention to have booster dose	Two categories: − yes − no	Hierarchical multiple regression	Significant association between higher interactive (p = .02) functional, critical, and overall (p < .001) VL and the intention to be vaccinated	Subgroup analysis: significant association between higher overall VL and the intention to be vaccinated in hesitant individuals (β = −0.036)	Confidence, availability, accessibility, obtainability of the booster dose
Gutierrez, 2022 #	COVID-19 VLS (adapted from HLVa-IT), continuous	- Functional - Interactive/critical	One question on the intention to have COVID-19 vaccination	Two categories: − yes − no	Non-parametric test	Non-significant association between higher functional VL and the intention to be vaccinated (p = .43); significant association between interactive/critical VL and the intention to be vaccinated (p < .01)	NA	NA
Kittipimpanon, 2022	COVID-19 VLS (adapted from HLVa-IT), continuous	- Overall	One question on the intention to have COVID-19 vaccination	Three categories: − will not have − not sure − will have for sure	Point biserial correlation tests	Significant association between higher VL and the intention to be vaccinated (p < .001)	NA	NA
Correa-Rodriguez, 2022 #	HLVa-IT, continuous	− Functional − Interactive/critical	One question on the intention to have COVID-19 vaccination	Two categories: − yes − no	Non-parametric test	Non-significant association between higher functional and interactive/critical VL and the intention to be vaccinated (p = .54 and p = .18)	NA	NA
Li, 2022	Adapted version of HLVa-IT, continuous	− Overall − Functional − Interactive − Critical	One question on the intention to have COVID-19 vaccination	Two categories: − yes − no	Non-parametric test	Non-significant association between higher functional, interactive, critical and overall VL and the intention to be vaccinated (p = .49, p = .80, p = .47 and p = .84)	NA	NA
Influenza
Biasio, 2020 (B) #	Adapted version of HLVa-IT, continuous	− Functional − Interactive/critical	One question on the intention to have the flu vaccination in the current year	Two categories: − yes − no	Kruskal Wallis	Significant association between higher functional and interactive/critical VL and the intention to be vaccinated (p < .001)	NA	NA
HPV
Suzuki, 2022	Ad hoc questionnaire, continuous	− Overall	One question on the timing of having the HPV vaccination	Two categories: − from immediately to 3 years − no intention to have a vaccine	MLR	Non-significant association between higher overall VL and the intention to be vaccinated in female sample (OR = 1.47, 95% CI: 0.75–2.87)	NA	Age, faculty, health habits
						Significant association between higher overall VL and the intention to be vaccinated in male sample (OR = 2.35, 95% CI: 1.23–4.47)	Significant association between higher overall VL and the intention to be vaccinated in male sample (aOR = 2.12, 95% CI: 1.02–4.41)

COVID-19: coronavirus disease 2019; HLVa-IT: Adult Vaccination Health Literacy in Italian; MLR: multivariable logistic regression. NA: not assessed; VL: vaccine literacy; β: beta coefficient.

#studies included in the meta-analysis.

Figure 2. Stratified standardized mean difference (SMD) of vaccine literacy (VL) scores of individuals willing to be or sure about being vaccinated vs. unwilling or unsure individuals. CI: confidence interval. COVID-19 VLS: COVID-19 vaccine literacy scale. HLVa-IT: Adult vaccination health literacy in Italian.

Figure 3. Sensitivity analysis of stratified standardized mean difference (SMD) of vaccine literacy (VL) scores of individuals willing to be or sure about being vaccinated vs. unwilling or unsure individuals. CI: confidence interval. COVID-19 VLS: COVID-19 vaccine literacy scale. HLVa-IT: Adult vaccination health literacy in Italian.

Table 3. Association between vaccine literacy (VL) and vaccination status.

First author, year	VL		Vaccination status		Statistical analysis	Main findings		Adjustment factors
	Measurement, coding	Domain	Measurement	Coding		Unadjusted analysis	Adjusted analysis
HPV
Lee, 2015	Ad hoc questionnaire, continuous	- Overall	One SRQ on completion of three doses of HPV vaccination	Two categories: - completion of the vaccination protocol (3 doses) - no completion (0, 1 or 2 doses)	MLR	NA	Significant association between higher VL and the completion of HPV vaccination in both groups (AAPI: aOR = 1.99; White: aOR = 2.40)	Age, born non in US, father’s education, HPV knowledge, medical visits, cancer history, number of sexual partners
Influenza + Pneumococcus + Tetanus
Biasio, 2020 (A)	HLVa-IT, continuous	- Functional - Interactive - Critical	Three SRQs on vaccination status (tetanus booster every 10 years, pneumococcal and influenza for ≥65 years)	Two categories: - having had ≥ 1 vaccine - having had no vaccine	Spearman’s rho and Kruskal Wallis	Significant association between higher functional VL and having had at least one vaccine (p = .04); non-significant association between higher interactive and critical VL and having had at least one vaccine (p = .13 and p = .17)	NA	NA
Influenza
Biasio, 2020 (B) #	Adapted version of HLVa-IT, continuous	- Functional - Interactive/critical	One SRQ on last season’s vaccination status	Two categories: - yes - no	Kruskal Wallis	Significant association between higher functional and interactive/critical VL and vaccination uptake (p < .001)	NA	NA
Krishnamurthy, 2021 #	Ad hoc questionnaire, continuous	- Interactive/critical	One SRQ on last season’s vaccination status	Two categories: - yes - no	Not reported	Non-significant association between higher interactive/critical VL and vaccination uptake (p > .05)	NA	NA
Correa-Rodriguez, 2022 #	HLVa-IT, continuous	- Functional - Interactive/critical	One SRQ on last season’s vaccination status	Two categories: - yes - no	Non-parametric test	Non-significant association between higher functional and interactive/critical VL and vaccination uptake (p = .42 and p = .77)	NA	NA
SARS-CoV-2
Yilmaz, 2022 #	COVID-19 VLS (adapted from HLVa-IT), continuous	- Overall - Functional - Interactive/critical	One SRQ on vaccination status	Two categories: - yes - no	t-Test	Significant association between higher functional VL and vaccination uptake (p = .03); non-significant association between higher interactive/critical and overall VL and vaccination uptake (p = .3 and p = .08)	NA	NA
Engelbrecht, 2022	Adapted version of HLVa-IT, continuous	- Functional - Interactive/critical	One SRQ on vaccination status	Two categories: - yes - no	MLR	Significant association between lower functional and interactive/critical VL and no vaccination uptake (OR = 1.74, 95% CI: 1.60–1.89) and OR = 1.90, 95% CI: 1.62–2.22)	Significant association between lower functional and interactive/critical VL and no vaccination uptake (aOR = 1.12, 95% CI: 1.01–1.23, and aOR = 1.35, 95% CI: 1.12–1.62)	Age, gender, race, education, employment, government’s ability to roll out vaccines
Kittipimpanon, 2022 #	COVID-19 VLS (adapted from HLVa-IT), continuous	- Overall	One SRQ on vaccination status	Two categories: - yes - no	t-Test	Non-significant association between higher overall VL and vaccination uptake (p = .13)	NA	NA
Li, 2022	Adapted version of HLVa-IT, continuous	- Overall - Functional - Interactive - Critical	One SRQ on vaccination status	Four categories: - first injection - first and second injections - booster injections - full vaccination	Non-parametric test	Non-significant association between higher functional, interactive, critical, and overall VL and vaccination uptake (p = .44, p = .19, p = .11 and p = .14)	NA	NA

VL: vaccine literacy; NA: not assessed; AAPI: Asian American and Pacific Islander; OR: odds ratio; aOR: adjusted odds ratio; CI: confidence interval; SRQ: self-reported Question; HLVa-IT: Adult Vaccination Health Literacy in Italian. MLR: multivariable logistic regression.

#:studies included in the meta-analysis.

Figure 4. Stratified standardized mean difference (SMD) of vaccine literacy (VL) scores of vaccinated vs. unvaccinated individuals. CI: confidence interval. COVID-19 VLS: COVID-19 vaccine literacy scale.