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Predictors of seasonal influenza vaccination among older adults in Thailand.

ABSTRACT: In advance of a large influenza vaccine effectiveness (VE) cohort study among older adults in Thailand, we conducted a population-based, cross-sectional survey to measure vaccine coverage and identify factors associated with influenza vaccination among older Thai adults that could bias measures of vaccine effectiveness.We selected adults ?65 years using a two-stage, stratified, cluster sampling design. Functional status was assessed using the 10-point Vulnerable Elders Survey (VES); scores ?3 indicated vulnerability. Questions about attitudes towards vaccination were based on the Health Belief Model. The distance between participants' households and the nearest vaccination clinic was calculated. Vaccination status was determined using national influenza vaccination registry. Prevalence ratios (PR) and 95% confidence intervals (CIs) were calculated using log-binomial multivariable models accounting for the sampling design.We enrolled 581 participants, of whom 60% were female, median age was 72 years, 41% had at least one chronic underlying illness, 24% met the criteria for vulnerable, and 23% did not leave the house on a daily basis. Influenza vaccination rate was 34%. In multivariable models, no variable related to functional status was associated with vaccination. The strongest predictors of vaccination were distance to the nearest vaccination center (PR 3.0, 95% CI 1.7-5.1 for participants in the closest quartile compared to the furthest), and high levels of a perception of benefits of influenza vaccination (PR 2.8, 95% CI 1.4-5.6) and cues to action (PR 2.7, 95% CI 1.5-5.1).Distance to vaccination clinics should be considered in analyses of influenza VE studies in Thailand. Strategies that emphasize benefits of vaccination and encourage physicians to recommend annual influenza vaccination could improve influenza vaccine uptake among older Thai adults. Outreach to more distant and less mobile older adults may also be required to improve influenza vaccination coverage.

SUBMITTER: Praphasiri P

PROVIDER: S-EPMC5706686 | biostudies-literature | 2017

REPOSITORIES: biostudies-literature

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Predictors of seasonal influenza vaccination among older adults in Thailand.

Praphasiri Prabda P Praphasiri Prabda P Ditsungnoen Darunee D Sirilak Supakit S Rattanayot Jarawee J Areerat Peera P Dawood Fatimah S FS Lindblade Kim A KA

PloS one 20171129 11

<h4>Background</h4>In advance of a large influenza vaccine effectiveness (VE) cohort study among older adults in Thailand, we conducted a population-based, cross-sectional survey to measure vaccine coverage and identify factors associated with influenza vaccination among older Thai adults that could bias measures of vaccine effectiveness.<h4>Method</h4>We selected adults ≥65 years using a two-stage, stratified, cluster sampling design. Functional status was assessed using the 10-point Vulnerable ...[more]

PMID: 29186159

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Project description:BackgroundWe measured the immunogenicity of seasonal trivalent inactivated influenza vaccines (IIV3) among older Thai adults and the effect of one-year prior vaccination status on immune responses.MethodAdults aged ≥65 years (n = 370) were vaccinated with Southern Hemisphere IIV3 in 2015. Hemagglutination inhibition assays were performed using goose red blood cells on sera collected from the participants at baseline and after 1, 6, and 12 months of vaccination. Prior year vaccination (in 2014) was verified with the national health security office database. We analyzed the associations between prior vaccination and geometric mean titers (GMT) at each time point using generalized linear regression on logged transformed titers, and seroprotection and seroconversion using Log-binomial regression.ResultsAt baseline, previously vaccinated participants (n = 203) had a significantly higher GMT and seroprotection against all three influenza strains than those previously unvaccinated (n = 167) (all p-values <0.001). Seroprotection rates were similar after one month in both groups for A(H1N1)pdm09 (adjusted risk ratio [aRR] 1.10, 95% CI 0.97-1.25), and A(H3N2) (aRR 1.08, 95% CI 0.87-1.33), but higher in previously vaccinated persons for B (aRR 1.20, 95% CI 1.08-1.32). At 12 months, 50% or more had seroprotection in previously vaccinated group with no difference between previously vaccinated or unvaccinated persons. Seroconversion was lower in the previously vaccinated group for A(H1N1)pdm09 (aRR 0.62, 95% CI 0.43-0.89), but did not differ between the two groups for A(H3N2) (aRR 0.94, 95% CI 0.69-1.28) and B (aRR 0.85, 95% CI 0.60-1.20).ConclusionInfluenza vaccination elicited good humoral response in older Thai adults. While seroconversion seemed attenuated in persons previously vaccinated for influenza A(H1N1)pdm09 (the only vaccine strain not to change), this was not apparent for influenza A(H3N2) and B, and prior vaccination was not associated with any inhibition in seroprotection.

Project description:BackgroundSeasonal influenza is a major cause of mortality worldwide. Routine immunization of children has the potential to reduce this mortality through both direct and indirect protection, but has not been adopted by any low- or middle-income countries. We developed a framework to evaluate the cost-effectiveness of influenza vaccination policies in developing countries and used it to consider annual vaccination of school- and preschool-aged children with either trivalent inactivated influenza vaccine (TIV) or trivalent live-attenuated influenza vaccine (LAIV) in Thailand. We also compared these approaches with a policy of expanding TIV coverage in the elderly.Methods and findingsWe developed an age-structured model to evaluate the cost-effectiveness of eight vaccination policies parameterized using country-level data from Thailand. For policies using LAIV, we considered five different age groups of children to vaccinate. We adopted a Bayesian evidence-synthesis framework, expressing uncertainty in parameters through probability distributions derived by fitting the model to prospectively collected laboratory-confirmed influenza data from 2005-2009, by meta-analysis of clinical trial data, and by using prior probability distributions derived from literature review and elicitation of expert opinion. We performed sensitivity analyses using alternative assumptions about prior immunity, contact patterns between age groups, the proportion of infections that are symptomatic, cost per unit vaccine, and vaccine effectiveness. Vaccination of children with LAIV was found to be highly cost-effective, with incremental cost-effectiveness ratios between about 2,000 and 5,000 international dollars per disability-adjusted life year averted, and was consistently preferred to TIV-based policies. These findings were robust to extensive sensitivity analyses. The optimal age group to vaccinate with LAIV, however, was sensitive both to the willingness to pay for health benefits and to assumptions about contact patterns between age groups.ConclusionsVaccinating school-aged children with LAIV is likely to be cost-effective in Thailand in the short term, though the long-term consequences of such a policy cannot be reliably predicted given current knowledge of influenza epidemiology and immunology. Our work provides a coherent framework that can be used for similar analyses in other low- and middle-income countries.

Project description:BackgroundThe COVID-19 pandemic has convoluted hesitancy toward vaccines, including the seasonal influenza (flu) vaccine. Because of COVID-19, the flu season has become more complicated; therefore, it is important to understand all the factors influencing the uptake of these vaccines to inform intervention targets. This article assesses factors related to the uptake of influenza and COVID-19 vaccines among adults in Tennessee.MethodsA cross-sectional, secondary data analysis of 1,400 adults was conducted in Tennessee. The adult sample came from two data sources: Data source 1 completed a baseline survey from January to March 2022, and data source 2 was completed from May to August 2022. Data on vaccine attitudes, facilitators and barriers, and communication needs were collected via random digit dial by Scientific Telephone Samples (STS). Two multivariable logistic regression models were used to estimate adjusted odds ratios (aORs) and 95% confidence intervals (CIs) to predict sociodemographic and overall vaccine-related factors associated with receipt or non-receipt (referent) of COVID-19 and influenza vaccines.ResultsApproximately 78% of the adult sample had received the COVID-19 vaccination. A significant positive association for COVID-19 vaccine uptake was seen among those who were older (aged 50-65) (aOR = 1.9; 95% CI: 1.2-3.2), Black (aOR = 2.0; 95% CI:1.3-2.8), and had a college education and higher (aOR = 2.3; 95% CI: 1.5-3.6). However, there was a significant negative association for persons reporting they were extremely religious (aOR = 0.5; 95% CI:0.3-0.9). Over 56% of the adult sample had received the influenza vaccination this season. Those who had a higher annual household income ($80,000+) (aOR = 1.9; 95% CI: 1.3-2.6) and had health insurance (aOR = 2.6; 95% CI: 1.4-4.8) had a significant positive association with influenza vaccine receipt. However, those who were employed part-time or were unemployed had a significant negative association for influenza vaccine receipt (aOR = 0.7; 95% CI: 0.5-0.9). Both COVID-19 and influenza vaccine receipt had strongly significant positive trends with increasing belief in effectiveness and trust (p < 0.0001) and strongly significant negative trends with higher levels of overall vaccine hesitancy (p < 0.0001).ConclusionStrategies to increase COVID-19 and influenza vaccination should be age-specific, focus on increasing geographical and financial access, and offer tailored messages to address concerns about these vaccines.

Project description:BackgroundWomen/females report more adverse events (AE) following immunization than men/males for many vaccines, including the influenza and COVID-19 vaccines. This discrepancy is often dismissed as a reporting bias, yet the relative contributions of biological sex and gender are poorly understood. We investigated the roles of sex and gender in the rate of AE following administration of the high-dose seasonal influenza vaccine to older adults (≥ 75 years) using an AE questionnaire administered 5-8 days post-vaccination. Participant sex (male or female) was determined by self-report and a gender score questionnaire was used to assign participants to one of four gender categories (feminine, masculine, androgynous, or undifferentiated). Sex steroid hormones and inflammatory cytokines were measured in plasma samples collected prior to vaccination to generate hypotheses as to the biological mechanism underpinning the AE reported.ResultsA total of 423 vaccines were administered to 173 participants over four influenza seasons (2019-22) and gender data were available for 339 of these vaccinations (2020-22). At least one AE was reported following 105 vaccinations (25%), by 23 males and 82 females. The majority of AE occurred at the site of injection, were mild, and transient. The odds of experiencing an AE were 3-fold greater in females than males and decreased with age to a greater extent in females than males. The effects of gender, however, were not statistically significant, supporting a central role of biological sex in the occurrence of AE. In males, estradiol was significantly associated with IL-6 and with the probability of experiencing an AE. Both associations were absent in females, suggesting a sex-specific effect of estradiol on the occurrence of AE that supports the finding of a biological sex difference.ConclusionsThese data support a larger role for biological sex than for gender in the occurrence of AE following influenza vaccination in older adults and provide an initial investigation of hormonal mechanisms that may mediate this sex difference. This study highlights the complexities of measuring gender and the importance of assessing AE separately for males and females to better understand how vaccination strategies can be tailored to different subsets of the population.

Project description:Background Women/females report more adverse events (AE) following immunization than men/males for many vaccines, including the influenza and COVID-19 vaccines. This discrepancy is often dismissed as a reporting bias, yet the relative contributions of biological sex and gender are poorly understood. We investigated the roles of sex and gender in the rate of AE following administration of the high-dose seasonal influenza vaccine to older adults (≥ 75 years) using an AE questionnaire administered 5-8 days post-vaccination. Participant sex (male or female) was determined by self-report and a gender score questionnaire was used to assign participants to one of four gender categories (feminine, masculine, androgynous, or undifferentiated). Sex steroid hormones and inflammatory cytokines were measured in plasma samples collected prior to vaccination to elucidate a possible biological mechanism for the AE reported. Results A total of 423 vaccines were administered to 173 participants over four influenza seasons (2019-22) and gender data were available for 339 of these vaccinations (2020-22). At least one AE was reported following 105 vaccinations (25%), by 23 males and 82 females. The majority of AE occurred at the site of injection, were mild, and transient. The odds of experiencing an AE were 3-fold greater in females than males and decreased with age to a greater extent in females than males. The effects of gender, however, were not statistically significant, supporting a central role of biological sex in the occurrence of AE. In males, estradiol was significantly associated with IL-6 and with the probability of experiencing an AE. Both associations were absent in females, suggesting a sex-specific effect of estradiol on the occurrence of AE that supports the finding of a biological sex difference. Conclusions These data support a larger role for biological sex than for gender in the occurrence of AE following influenza vaccination in older adults and provide an initial investigation of hormonal mechanisms that may mediate this sex difference. This study highlights the complexities of measuring gender and the importance of assessing AE separately for males and females to better understand how vaccination strategies can be tailored to different subsets of the population.

Dataset Information

Predictors of seasonal influenza vaccination among older adults in Thailand.

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Predictors of seasonal influenza vaccination among older adults in Thailand.

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