SARS-CoV-2 Antibody Dynamics after COVID-19 Vaccination and Infection: A Real-World Cross-Sectional Analysis.

The Coronavirus disease 2019 (COVID-19) pandemic, caused by Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2), continues to surge despite the widespread use of vaccination. In Thailand, more than 77% and 39% of the population received two doses and three doses of COVID-19 vaccines as of December 2022, respectively. In addition, during the Omicron predominant period in 2022, more than 70% of Thai individuals have been infected. To gain comprehensive insight into SARS-CoV-2 antibody dynamics following vaccination or following vaccination and infection (hybrid immunity), we performed a cross-sectional analysis of sera samples from individuals who received COVID-19 vaccination and/or have been infected with COVID-19 in Thailand between January 2021 and December 2022. A total of 4126 samples were collected. Humoral immunity was evaluated by quantifying the immunoglobulin (including IgG, IgM, and IgA isotypes) specific to the SARS-CoV-2 receptor-binding domain (RBD) or Ig anti-RBD. The results showed that individuals who received two-dose vaccination alone had lower levels of Ig anti-RBD, which rapidly waned over time. To restore the waning antibody, a third dose vaccination is recommended for uninfected individuals who have only received 2 doses.

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.

The impact of COVID-19 and control measures on public health in Thailand, 2020.

BACKGROUND: The COVID-19 virus has been an emerging disease causing global outbreaks for over a year. In Thailand, transmission may be controlled by strict measures that could positively and negatively impact physical health and suicidal behavior. METHODS: The incidence of COVID-19 was retrieved from the Department of Disease Control (DDC). The impact of viral diseases was retrieved from the open-source of the DDC and King Chulalongkorn Memorial Hospital. The road accidents data were from the Thai Ministry of Transport. The suicidal behavior data were obtained from the Department of Mental Health. We compared data from the year 2019 with the pandemic COVID-19 outbreak period in 2020, before lockdown, during lockdown, easing, and new wave period using unpaired t-test and least-squares linear regression. We compared the impact of the outbreak on various data records in 2020 with corresponding non-outbreak from 2019. RESULTS: There was a significant decline in cases of influenza (p < 0.001) and norovirus (p = 0.01). However, there was no significant difference in RSV cases (p = 0.17). There was a dramatic increase in attempt to suicides and suicides (p < 0.001). There was no impact on roadside accidents and outpatient department visits. DISCUSSION: The extensive intervention measures during lockdown during the first wave positively impacted total cases for each period for acute respiratory and gastrointestinal tract diseases, car accidents, and injuries and negatively impacted indicators of suicidal behavior. The data support government policies that would be effective against the next outbreak by promoting the "new normal" lifestyle.

COVID-19 Transmission among Healthcare Workers at a Quarantine Facility in Thailand: Genomic and Outbreak Investigations.

During the COVID-19 pandemic, Thailand implemented a quarantine program at approved quarantine facilities for every international traveler. Here, we report an epidemiological and genomic investigation of a COVID-19 cluster consisting of seven healthcare workers (HCWs) at a quarantine facility and its partnered hospital in Thailand. Outbreak investigations were implemented to obtain contact tracing data and to establish chains of transmission. Genomic sequencing of SARS-CoV-2 with samples within the cohort was performed. Investigations of 951 HCWs and staff with quarantined travelers were implemented to determine the chain of transmission. Genomic and outbreak investigations identified the international travelers infected with the B.1.1.31 SARS-CoV-2 lineage as the source of this outbreak. The genomic data and the investigated timeline revealed a putative transmission chain among HCWs, pointing toward the transmission via the use of common living quarters at the investigated quarantine site. The evaluation of this cohort has led to a policy recommendation on quarantine facility management. International travel quarantine is an important strategy to contain importation of COVID-19 cases. However, a quarantine facility is likely to become a potential hotspot, requiring thorough preventive measures. Reducing the exposure risk by providing private living quarters and scheduling clinical duties at a quarantine site separated from the conventional healthcare workforce have been implemented.

Time to Serological Cure and Associated Factors Among Syphilis Patients With and Without HIV in a Sexually Transmitted Infections Center, Thailand.

BACKGROUND: Together with clinical correlation, nontreponemal titers are used to monitor treatment outcomes. Syphilis patients with HIV and without HIV coinfection were found to have different serological responses after treatment. This study aims to determine time to serological cure for treatment of syphilis and factors associated with it in patients with and without HIV. METHOD: A descriptive study of syphilis patients who visited Bangrak STIs Center between January 1, 2007, and December 31, 2016. Univariate analysis was done to determine factors associated with serological outcomes. Survival curve analysis and multivariate Cox regression analysis were applied to compare time to serological cure between patients with various characteristics. RESULTS: Of 497 syphilis patients, 62.1% had serological cure, 2.2% had nonresponse, 4.6% had treatment failure or reinfection, 9.9% had serofast status, and 21.2% were undetermined because of loss to follow-up. The time to serological cure was 110 days (95% confidence interval [CI], 59-163 days) and 102 days (95% CI, 94-110 days) among patients with HIV and without HIV, respectively (P = 0.162). Time to serological cure was significantly faster in early syphilis and baseline titer ≥1:32. After adjustment with the Cox regression model, patients with early syphilis were associated with serological cure with a hazard ratio of 1.75 (95% CI, 1.32-2.32). Time to serological cure among early syphilis patients was significantly longer in HIV-positive than HIV-negative patients (P = 0.002), whereas no difference was observed in late syphilis (P = 0.104). CONCLUSION: Early syphilis was associated with faster time to serological cure. HIV patients with early syphilis took longer time to reach serological cure than did HIV-negative patients, whereas no such a difference was observed in late syphilis.

Searching for randomised controlled trials and clinical controlled trials in Thai online bibliographical biomedical databases.

BACKGROUND: Thailand is a poor but highly literate country in South-East Asia with over 60 million people. A lot of biomedical research is undertaken but dissemination is limited. OBJECTIVES: To identify relevant Thai bibliographic databases and investigate accessibility, functionality and content, particularly in relation to randomised controlled trials (RCTs) and clinical controlled trials (CCTs). METHODS: A systematic search for institutions productive of research and the databases in their libraries. Search each accessible database in both Thai and English, recording the functionality and content. Assess accessibility of the retrieved RCTs or CCTs by comparing to PubMed holdings. RESULTS: We found 32 different databases (29 accessible in UK) of various sizes, coverage and functionality but many with unique records of RCTs and CCTs (total, n=781). Two hundred and nine of 781 trials were accessible on PubMed (27%). However, 641 of the 781 trial records contain text in both English and Thai (82%) and 112 records were solely English (14%). CONCLUSIONS: Those undertaking comprehensive searches for RCTs/CCTs should, in addition to a PubMed, search the Thai Medical Index and Thai Index Medicus databases, and the Khon Kaen University Library Catalogue.