Seasonal influenza vaccine coverage among high-risk populations in Thailand, 2010–2012

AbstractBackgroundThe Advisory Committee on Immunization Practice of Thailand prioritizes seasonal influenza vaccinations for populations who are at highest risk for serious complications (pregnant women, children 6 months–2 years, persons ≥65 years, persons with chronic diseases, obese persons), and healthcare personnel and poultry cullers. The Thailand government purchases seasonal influenza vaccine for these groups. We assessed vaccination coverage among high-risk groups in Thailand from 2010 to 2012.MethodsNational records on persons who received publicly purchased vaccines from 2010 to 2012 were analyzed by high-risk category. Denominator data from multiple sources were compared to calculate coverage. Vaccine coverage was defined as the proportion of individuals in each category who received the vaccine. Vaccine wastage was defined as the proportion of publicly purchased vaccines that were not used.ResultsFrom 2010 to 2012, 8.18 million influenza vaccines were publicly purchased (range, 2.37–3.29 million doses/year), and vaccine purchases increased 39% over these years. Vaccine wastage was 9.5%. Approximately 5.7 million (77%) vaccine doses were administered to persons ≥65 years and persons with chronic diseases, 1.4 million (19%) to healthcare personnel/poultry cullers, 82,570 (1.1%) to children 6 months–2 years, 78,885 (1.1%) to obese persons, 26,481 (0.4%) to mentally disabled persons, and 17,787 (0.2%) to pregnant women. Between 2010 and 2012, coverage increased among persons with chronic diseases (8.6% versus 14%; p<0.01) and persons ≥65 years (12%, versus 20%; p<0.01); however, coverage decreased for mentally disabled persons (6.1% versus 4.9%; p<0.01), children 6 months–2 years (2.3% versus 0.9%; p<0.01), pregnant women (1.1% versus 0.9%; p<0.01), and obese persons (0.2% versus 0.1%; p<0.01).ConclusionsFrom 2010 to 2012, the availability of publicly purchased vaccines increased. While coverage remained low for all target groups, coverage was highest among persons ≥65 years and persons with chronic diseases. Annual coverage assessments are necessary to promote higher coverage among high-risk groups in Thailand

Predictors of seasonal influenza vaccination among older adults in Thailand

<div><p>Background</p><p>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.</p><p>Method</p><p>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.</p><p>Result</p><p>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).</p><p>Conclusion</p><p>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.</p></div

Tolerability of trivalent inactivated influenza vaccine among pregnant women, 2015

Abstract Background Thailand recommends influenza vaccination among pregnant women. We conducted a cohort study to determine if the prevalence of adverse events following immunization (AEFIs) with influenza vaccine among Thai pregnant women was similar to that often cited among healthy adults. Methods Women who were ≥17 gestational weeks and ≥18 years of age were recruited. Demographic and health history data were collected using structured questionnaires. Women were provided with symptom diary, ruler to measure local reaction(s), and thermometer to measure body temperature. AEFIs were defined as any new symptom/abnormality occurring within four weeks after vaccination. The diaries were abstracted for frequency, duration, and level of discomfort/inconvenience of the AEFIs. Serious adverse events (SAEs) and the likelihood of AEFIs being associated with vaccination were determined using standard definitions. Results Among 305 women enrolled between July–November 2015, median age was 29 years. Of these, 223 (73%) were in their third trimester, 271 (89%) had completed secondary school or higher, and 20 (7%) reported ≥1 pre-existing conditions. AEFIs were reported in 134 women (44%; 95% confidence interval [CI] 38–50%). Soreness at the injection site (74, 24%; CI 19–29%), general weakness (50, 16%; CI 12–21%), muscle ache (49, 16%; CI 12–21%), and headache (45, 15%; CI 1–19%) were most common. Of those with AEFIs, 120 (89%) reported symptom/abnormality occurred on day 0 or day 1 following vaccination. Ten women (7%) reported the AEFIs affected daily activities. The AEFIs generally spontaneously resolved within 24 h of onset. There were two vaccine-unrelated SAEs. Of 294 women with complete follow-up, 279 (95%) had term deliveries, 12 (4%) had preterm deliveries, and 3 (1%) had miscarriage or stillbirth. Conclusion In our cohort, AEFIs with influenza vaccine occurred with similar frequency to those reported among healthy adults in other studies, and were generally mild and self-limited. No influenza vaccine-associated SAEs were identified

Forest plot of mean standardized scores* and 95% confidence intervals of the Health Belief Model constructs by vaccination status, Thailand (n = 581).

<p>*Standardized scores (Z scores) were calculated to account for the different number of items comprising each HBM constructs (<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0188422#pone.0188422.s001" target="_blank">S1 Table</a>), such that all constructs of HBM had a mean of 0 and standard deviation of 1.</p

Descriptive characteristics of survey participants by 2014 influenza vaccination status, Thailand^*.

<p>Descriptive characteristics of survey participants by 2014 influenza vaccination status, Thailand^{<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0188422#t001fn001" target="_blank">*</a>}.</p

Factors associated with vaccination among survey participants in 2014 (n = 581).

<p>Factors associated with vaccination among survey participants in 2014 (n = 581).</p

Streptococcus suis Infection in Hospitalized Patients, Nakhon Phanom Province, Thailand

In Nakhon Phanom, Thailand, we identified 38 hospitalized patients with Streptococcus suis infection during 2006–2012. Deafness developed in 12 patients; none died. Thirty-five reported recent exposure to pigs/pork. Annual incidence was 0.1–2.2 cases/100,000 population (0.2–3.2 in persons >20 years of age). Clinicians should consider S. suis infection in areas where pig exposure is common

Comparison of incidence and cost of influenza between healthy and high-risk children <60 months old in Thailand, 2011-2015

<div><p>Introduction</p><p>Thailand recommends influenza vaccination for children aged 6 months to <36 months, but investment in vaccine purchase is limited. To inform policy decision with respect to influenza disease burden and associated cost in young children and to support the continued inclusion of children as the recommended group for influenza vaccination, we conducted a prospective cohort study of children in Bangkok hospital to estimate and compare influenza incidence and cost between healthy and high-risk children.</p><p>Methods</p><p>Caregivers of healthy children and children with medical conditions (‘high-risk’) aged <36 months were called weekly for two years to identify acute respiratory illness (ARI) episodes and collect illness-associated costs. Children with ARI were tested for influenza viruses by polymerase chain reaction. Illnesses were categorized as mild or severe depending on whether children were hospitalized. Population-averaged Poisson models were used to compare influenza incidence by risk group. Quantile regression was used to examine differences in the median illness expenses.</p><p>Results</p><p>During August 2011-September 2015, 659 healthy and 490 high-risk children were enrolled; median age was 10 months. Incidence of mild influenza-associated ARI was higher among healthy than high-risk children (incidence rate ratio [IRR]: 1.67; 95% confidence interval [CI]: 1.13–2.48). Incidence of severe influenza-associated ARI did not differ (IRR: 0.40; 95% CI: 0.11–1.38). The median cost per mild influenza-associated ARI episode was $22 among healthy and$25 among high-risk children (3–4% of monthly household income; difference in medians: -$1; 95$9 to $6). The median cost per severe influenza-associated ARI episode was$232 among healthy and $318 among high-risk children (26–40$352 to $571).</p><p>Conclusions</p><p>Compared to high-risk children, healthy children had higher incidence of mild influenza-associated ARI but not severe influenza-associated ARI. Costs of severe influenza-associated ARI were substantial. These findings support the benefit of annual influenza vaccination in reducing the burden of influenza and associated cost in young children.</p></div

Number of acute respiratory illnesses (ARI) and influenza-associated ARI among children enrolled in a pediatric respiratory infection cohort in Thailand.

<p>ARI: acute respiratory illness. *partial season.</p

Median cost per acute respiratory illness episode adjusted for distance from residence to the study site in children enrolled in a pediatric respiratory infection cohort in Thailand.

<p>Median cost per acute respiratory illness episode adjusted for distance from residence to the study site in children enrolled in a pediatric respiratory infection cohort in Thailand.</p