SARS-CoV-2 seroprevalence among cancer patients and household caregivers in a cancer hospital: Cross-sectional survey after the second COVID-19 wave in Thailand.

Objectives: Patients with cancer may be at an increased risk of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and experience more severe outcomes. Low vaccine coverage in the early phase of the coronavirus disease 2019 (COVID-19) pandemic meant that personal and social measures to reduce viral spread were the only methods of lowering the risk of infection among cancer patients. This study explored the prevalence of SARS-CoV-2 antibodies in cancer patients and caregivers in a cancer hospital after the second COVID-19 outbreak in Thailand. Study design: Cross-sectional study. Methods: A SARS-CoV-2 seroprevalence cross-sectional survey was conducted among 200 cancer patients and 200 household caregivers in a tertiary cancer care hospital in Bangkok, Thailand. The survey took place between 4 March and May 31, 2021 - a time period covering the end of the second COVID-19 wave and the early phase of the third wave in Thailand. Results: Rigorous personal and social measures to reduce viral spread among cancer patients and caregivers lead to an extremely low prevalence of SARS-CoV2 infection (0% among cancer patients and 1% among household caregivers). Conclusion: This study demonstrates the importance of social distancing and personal hygiene measures for the prevention of SARS-CoV-2 infection, even when vaccine coverage is low.

Safety after BBIBP-CorV (Sinopharm) COVID-19 Vaccine in Adolescents Aged 10-17 Years in Thailand.

Coronavirus disease 2019 affected child health and impacted learning because of the resulting onsite school closures. This prospective cohort study included children aged 10-17 who received two 4 µg doses of BBIBP-CorV administered intramuscularly 21-28 days apart. To assess vaccine safety, 36,808 participants were then followed with paper- and web-based online questionnaire surveys that captured local and systemic reactogenicities following vaccine administration on days 1, 7, and 30. Among participants, 76% (27,880) reported reactogenicity within the first 24 h and 7 days following the first dose. Half (51.41%) of participants experienced pain at the injection site; the majority of cases were mild in severity. Injection site tenderness (37.93%) was another common local reaction. Fatigue (37.89%), myalgia (33.56%), and headache (26.76%) were the most common systemic reactions. On days 2-7 after the first dose, 25.85% of participants experienced adverse reactions. Following the second dose, reactogenicity was 7.6% and 1.09% within 24 h and between days 2-7. The majority of reactions were of mild to moderate severity. We report that two doses of the BBIBP-CorV caused mild to moderate side effects in adolescents in Thailand. The findings confirm the vaccine's safety profile in this age group.

Reactogenicity, immunogenicity, and humoral immune response dynamics after the third dose of heterologous COVID-19 vaccines in participants fully vaccinated with inactivated vaccine.

INTRODUCTION: Immunogenicity after the CoronaVac vaccine remains uncertain, especially regarding infections with the coronavirus variants of concern and waning immunity. METHODS: This was a single-center, open-label clinical trial designed to assess the immunogenicity and safety of BBIBP-CorV, AZD1222, or BNT162b2 as the third vaccination. The key eligible criteria were individuals at least 18 years old who were fully vaccinated with two doses of CoronaVac vaccine for 2-4 months. The primary endpoint was the ratio of the geometric mean concentration (GMC) of the total anti-receptor binding domain (RBD) antibody post-vaccination compared with that pre-vaccination. The secondary endpoint was reactogenicity within 7 days. RESULTS: Forty-one participants received AZD1222, 40 received BBIBP-CorV, and 40 received BNT162b2. The GMC of anti-RBD antibody at 2 weeks post-vaccination was 31,138.67 binding antibody units (BAU)/mL for BNT162b2, 6,412.10 BAU/mL for AZD1222, and 1,092.7 BAU/mL for BBIBP-CorV. Compared with pre-vaccination, the ratio of anti-RBD concentration was 690.24 for BNT162b2, 130.02 for AZD1222, and 17.79 for BBIBP-CorV. No potentially life-threatening adverse reaction were observed within 7 days. CONCLUSION: A third vaccination with the heterologous vaccine, BBIBP-CorV, AZD1222, or BNT162b2, can elicit a robust immune response, without serious adverse events in participants fully vaccinated with the CoronaVac vaccine.

Safety and Immunogenicity of the BBIBP-CorV Vaccine in Adolescents Aged 12 to 17 Years in the Thai Population: An Immunobridging Study.

Adolescents can develop a severe form of Coronavirus disease 2019 (COVID-19), especially with underlying comorbidities. No study has examined the efficacy or effectiveness of inactivated COVID-19 vaccines in adolescents. This single-center, prospective cohort study was performed to evaluate the safety and effectiveness of an inactivated COVID-19 vaccine in adolescents using the immunobridging approach at Chulabhorn Hospital. The key eligibility criterion was a healthy clinical condition or stable pre-existing comorbidity. The anti-receptor-binding domain (anti-RBD) antibody concentration at 4 weeks after dose 2 of the vaccine was compared between participants aged 12 to 17 years and those aged 18 to 30 years. Safety profiles included adverse events within 7 days after each dose of the vaccine and any adverse events through 1 month after dose 2 of the vaccine. In the adolescent and adult cohorts, the geometric mean concentration of anti-RBD antibody was 102.9 binding antibody unit (BAU)/mL (95% CI, 91.0−116.4) and 36.9 BAU/mL (95% CI, 30.9−44.0), respectively. The geometric mean ratio of the adolescent cohort was 2.79 (95% CI, 2.25−3.46, p < 0.0001) compared with the adult cohort, meeting the non-inferiority criterion. The reactogenicity was slightly lower in the adolescent than in the adult cohort. No serious adverse events occurred. The inactivated COVID-19 vaccine appears safe and effective in adolescents.

Persistence of immunogenicity, contributing factors of an immune response, and reactogenicities after a single dose of the ChAdOx1 (AZD1222) COVID-19 vaccine in the Thai population.

INTRODUCTION: Due to the vaccine's short supply and the efficacy of a single dose of the ChAdOx1 (AZD1222) vaccine, many governments delayed the interval between prime and boost dose from 4 to 8-12 weeks. However, the waning of immune response in this period is a concern. This study evaluated the durability, contributing factors of anti-RBD antibody concentration, and reactogenicities after the single dose of AZD1222 vaccine in the Thai population. METHODS: This was a single-center, prospective cohort study at Chulabhorn Hospital, Bangkok, Thailand. Individuals 18 years or older who were negative for anti-SARS-CoV-2 antibody were eligible. Anti- receptor-binding domain antibody concentrations were tested at least three weeks after the first vaccination and immediately before the second dose of vaccine. Information on reactogenicities was obtained via a questionnaire sent by a short message service. RESULTS: Anti-RBD Antibody concentration at 2 and 3 months post-vaccination were significantly higher than at 1 months post-vaccination (20.14 BAU/mL (95%CI; 16.37, 24.77) at 1 month, 48.08 BAU/mL (95%CI; 42.76, 54.08) at 2 month, and 65.01 BAU/mL (95%CI; 58.88,71.61) at 3 month). Adverse events occurred in approximately 60% of participants. Factors influencing vaccine immunogenicity include age, sex, the time elapsed from the first dose of vaccine, and underlying disease with diabetes and hematologic disease. CONCLUSION: A single dose of AZD1222 could elicit immune responses that did not decline within three months in Thai individuals. These data support the public health strategy of a delay between the prime and boost dose of AZD1222 of 4 to 12 weeks.

Immunogenicity and reactogenicity after heterologous prime-boost vaccination with CoronaVac and ChAdox1 nCov-19 (AZD1222) vaccines.

Mass vaccination with a safe and effective vaccine may be the best way to control the COVID-19 pandemic. Heterologous prime-boost vaccination with the CoronaVac and AZD1222 vaccines may increase the immunogenicity elicited by either vaccine alone. This study sought to compare the immunogenicity of a heterologous CoronaVac and AZD1222 prime-boost with a homologous CoronaVac prime-boost. From July 13 to September 2, 2021, 88 participants were enrolled in the study. Half (n = 44) of the participants were assigned to the AZD1222/CoronaVac cohort and half were assigned to the CoronaVac/AZD1222 cohort. Both cohorts had a prime-boost interval of 4 weeks. A control group of 136 health care personnel who received the homologous CoronaVac/CoronaVac prime-boost was matched by age and sex to the experimental cohorts. The primary endpoint was the geometric mean ratio (GMR) of the anti-receptor binding domain (RBD) antibody concentration 4 weeks after the booster dose was administered. The CoronaVac/CoronaVac cohort served as the reference group. Baseline age and sex were similar, and the median age was 42.5 years. The GMR was 2.58 (95% confidence interval [CI] 1.80-3.71) and 8.69 (95% CI 6.05-12.47) in the AZD1222/CoronaVac and CoronaVac/AZD1222 cohorts, respectively. Reactogenicity was similar following prime and booster doses with the same vaccine. Findings indicated that the heterologous CoronaVac and AZD1222 prime-boost combination elicited a more robust immune response than the homologous CoronaVac prime-boost. While both heterologous prime-boost combinations showed similar reactogenicity, the immunogenicity of the CoronaVac/AZD1222 cohort was higher, indicating that the order of prime-boost vaccine administration was important.

Immunogenicity and safety of an intradermal fractional third dose of ChAdOx1 nCoV-19/AZD1222 vaccine compared with those of a standard intramuscular third dose in volunteers who previously received two doses of CoronaVac: A randomized controlled trial.

INTRODUCTION: The CoronaVac vaccine is widely used in Thailand to combat the coronavirus disease 2019 (COVID-19) pandemic. The limited immunogenicity of this vaccine is a concern, especially because of expanding delta variant outbreaks. A third boost may enhance antiviral immune responses. METHODS: This non-inferiority randomized controlled trial evaluated the immunogenicity and safety of an intradermal (ID) fractional third dose of AZD1222 vaccine compared with those of a standard intramuscular (IM) third dose. Participants were enrolled from August 9, 2021 to August 13, 2021 at Chulabhorn Hospital, Bangkok, Thailand. The eligibility criteria were age 18 years or older and prior two-dose Coronavac vaccination completed at least 2 months previously. Participants were randomly assigned to one of three groups by block randomization: (i) standard dose by IM administration (IM), (ii) 20% of the standard dose ID (ID1), or (iii) 40% of the standard dose ID (ID2). The primary endpoint was the geometric mean ratio of anti-receptor binding domain antibody in the ID1/ID2 vs. the IM groups 14 days post-vaccination. RESULTS: A total of 125 participants were randomized (IM, n = 41; ID1, n = 41; and ID2, n = 43). One participant was lost to follow-up by day 14 post-vaccination in the ID1 group. The geometric mean ratio (95% confidence interval) of anti-receptor binding domain antibody was 0.94 (0.80-1.09) in the ID1 group and 1.28 (0.95-1.74) in the ID2 group. Immunogenicity in both ID groups met the non-inferiority criteria. Local adverse events were more common in the ID groups than in the IM group but were mostly mild to moderate in severity. CONCLUSION: An ID fractional third dose of AZD1222 was non-inferior to a standard IM third dose among individuals previously vaccinated with CoronaVac. Adverse events associated with the ID fractional third dose included mild to moderate local site reactions. This vaccination strategy may help conserve vaccine supply.

High prevalence of advanced colorectal neoplasia in the Thai population: a prospective screening colonoscopy of 1,404 cases.

BACKGROUND: Increasing morbidity and mortality from colorectal cancer is evident in recent years in the developing Asian nations. Particularly in Thailand and most neighbouring low-income countries, screening colonoscopy is not yet recommended nor implemented at the national policy level. METHODS: Screening colonoscopy was offered to 1,500 healthy volunteers aged 50-65 years old who were registered into the program between July 2009 and June 2010. Biopsy and surgery was performed depending on the identified lesions. Fecal immunochemical tests (FIT) were additionally performed for comparison with colonoscopy. RESULTS: There were 1,404 participants who underwent colonoscopy. The mean age of the cohort was 56.9 ± 4.2 years and 69.4 % were females. About 30 % (411 cases) of all colonoscopies had abnormal colonoscopic findings, and of these, 256 cases had adenomatous polyps. High risk adenomas (villous or tubulovillous or high grade dysplasia or size > 1 cm or > 3 adenomatous polyps) were found in 98 cases (7 %), low risk adenoma in 158 cases (11.3 %), and hyperplastic polyps in 119 cases (8.5 %). Eighteen cases (1.3 %) had colorectal cancer and 90 % of them (16 cases) were non-metastatic including five stage 0 cases, seven stage I cases, and four stage IIA cases. Only two cases had metastasis: one to regional lymph nodes (stage IIIB) and another to other organs (stage IVA). The most common cancer site was the distal intestine including rectum (7 cases, 38.9 %) and sigmoid colon (7 cases, 38.9 %). Ten colorectal cancer cases had positive FIT whereas 8 colorectal cancer cases were FIT-negative. The sensitivity and specificity of FIT was 55.6 % and 96.2 %, respectively, while the positive predictive value was 16.4 % and negative predictive value was 99.4 %. The overall survival of colorectal cancer cases at 5-year was 83.3 %. CONCLUSION: High prevalence of colorectal cancer and high-risk adenoma was found in the Thai population aged 50-65 years old by screening colonoscopy. FIT was not sensitive enough to detect colorectal cancer in this asymptomatic cohort. Integration of screening colonoscopy into the national cancer screening program should be implemented to detect early cases of advanced colorectal neoplasia and improve survival of colorectal cancer patients in Thailand.

Ultrasound screening for cholangiocarcinoma could detect premalignant lesions and early-stage diseases with survival benefits: a population-based prospective study of 4,225 subjects in an endemic area.

BACKGROUND: Thailand has a high incidence of cholangiocarcinoma (CCA), particularly in the north and northeastern regions. Most CCA patients come at a late, unresectable stage and presently no optimal screening test for CCA has been established. We determined the prevalence of CCA in a remote northern village and explored if screening could lead to early detection and survival benefits. METHODS: A 5-year population-based study was started in October, 2011 for consented Thai individuals, aged 30-60 years. The screening program comprised blood testing, stool examination and serial ultrasonography every 6 months. RESULTS: During the first 3 years, 4,225 eligible individuals were enrolled. CCA was detected in 32 patients, with a mean age of 51.9 years (41-62 years), and 21/32 cases were at a curative resectable stage. The prevalence rate of CCA was 165.7 per 100,000 and one- and two-year incidence rate was 236.7/100,000 and 520.7/100,000, respectively. One- and 2-year overall survival rates of CCA patients were 90.9 and 61.5 %, respectively. Prognosis was better in resectable cases with 100 % 1-year and 77.8 % 2-year survival rates. Interestingly, premalignant pathological lesions (stage 0) were identified in 11 cases with 100 % 3-year survival rate. Serum biomarkers and alkaline phosphatase were not sufficient to detect early-stage disease. In 22 patients, stool samples were positive for Opistorchis viverrini, based on polymerase chain reaction. CONCLUSION: Detection of premalignant lesions and early-stage resectable CCA by ultrasonography resulted in improved clinical outcome. Ultrasonography should be offered as a first screening tool for CCA in an endemic area until other useful biological markers become available.