Seroprevalence of anti-SARS-CoV-2 antibodies and associated factors among household contacts of COVID-19 confirmed cases in Bangkok, Thailand

Background: High COVID-19 transmission among household (HH) contacts of infected cases were reported with seroprevalence varying from 5.5% to 57.2% worldwide. Data on seroprevalence among HH contacts and factors associated with seropositivity in Thailand are limited. Objectives: To determine the seroprevalence and factors associated with anti-SARS-CoV-2 antibodies among HH contacts of COVID-19 confirmed cases. Materials and methods: Data on confirmed COVID-19 cases (primary cases) in Bangkok from March 2020–July 2021 were retrieved from Institute for Urban Disease Control and Prevention. Primary cases were contacted within 14 days of testing positive for permission to contact their HH contacts via telephone. HH contacts were then recruited to complete questionnaires about demographics, and risk factors and blood was collected and tested for total immunoglobulin antibody against SARS-CoV-2 spike S1 protein. Factors associated with seropositivity were analysed by logistic regression. Results: Eligible participants of 452 HH contacts of infected cases in Bangkok were contacted. Seroprevalence was 20.5% among HH contacts. Factors associated with seropositivity after multivariate analysis were relationship to index case (being other relatives to index case (other than close relatives/spouse) [aOR 4.04, 95% CI; 1.15, 14.14, p.029] and being a co-worker to index cases [aOR 0.16, 95% CI; 0.045, 0.60, p.006]), always staying in the same room with index case [aOR 5.64, 95% CI; 1.95, 16.34, p.001], sharing utensil [aOR 0.25, 95% CI; 0.074, 0.82, p.023], and participation in leisure activities together with index case [aOR 4.77, 95% CI; 1.47, 15.51, p.009]. Conclusion: Serological investigation can be used in detecting COVID-19 infection in conjunction with other molecular techniques. It is a useful tool for studies on seroprevalence in a population as well as seroconversion after a vaccination campaign. Sharing living environments are associated with seropositivity in HH contacts. Nevertheless, individual practices can be affected by awareness, cultural differences, and control measures implemented by each country

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

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

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

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

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

Do Thai Physicians Recommend Seasonal Influenza Vaccines to Pregnant Women? A Cross-Sectional Survey of Physicians’ Perspectives and Practices in Thailand

<div><p>Background</p><p>Physicians play a major role in influencing acceptance and uptake of vaccines. However, little is known about physicians’ perspectives on influenza vaccination of pregnant women in Thailand, for whom vaccine coverage is estimated at <1%.</p><p>Method</p><p>In 2013, a self-administered questionnaire on physicians’ perceptions, attitudes and practices related to influenza vaccination for pregnant women was distributed to 1,134 hospitals with an antenatal care clinic (ANC) in Thailand. At each hospital, one physician working at the ANC completed the survey. Predictors of routine recommendation of influenza vaccine were analyzed utilizing log-binomial regression.</p><p>Results</p><p>A total of 580 (51%) complete responses were received from physicians practicing at ANCs. A favorable attitude towards vaccination was expressed by 436 (75%) physicians, however only 142 (25%) reported routinely recommending influenza vaccine to pregnant women in their current practice. Physicians were more likely to recommend influenza vaccine routinely when they had more than three years of practice (prevalence ratio [PR] 1.9, 95% CI 1.2–2.3), had treated pregnant women for influenza (PR 1.8, 95% CI 1.3–2.7), perceived the influenza vaccine to be effective (moderate level: PR 1.6, 95% CI 1.1–2.4; high level: PR 1.9, 95% CI 1.3–2.9) and were aware of the Ministry of Public Health’s (MOPH) recommendation of influenza vaccination in pregnancy (PR 1.3, 95% CI 1.1–1.7). Vaccine not being available, perception that policy was ambiguous and lack of awareness of MOPH recommendations were the most commonly cited barriers to routine recommendation of influenza vaccine.</p><p>Conclusion</p><p>Despite a national policy to vaccinate pregnant women for influenza, only 25% of Thai physicians working in ANCs routinely recommend vaccination. Strategies are needed to increase vaccine availability and free vaccine services, address clinician concerns over vaccine effectiveness and expand healthcare provider awareness of MOPH recommendations.</p></div

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 reasons for not recommending vaccines to pregnant women by Thai physicians in public and private hospitals (N = 401).

<p>Comparison of reasons for not recommending vaccines to pregnant women by Thai physicians in public and private hospitals (N = 401).</p