Seroprevalence of hepatitis A virus antibodies among children and adolescents living in Northern Thailand: an implication for hepatitis A immunization.

This cross-sectional study aimed to assess seroprevalence of hepatitis A virus (HAV) antibodies and identify factors associated with HAV seropositivity among children and adolescents aged 1-18 years who resided in Chiang Mai, Thailand. Sociodemographic characteristics, sanitation/hygiene, and history of HAV vaccination were collected. Anti-HAV IgG antibody was determined, and a level ≥ 1.0 S/CO defined HAV seropositivity. We enrolled 300 participants; median age 8.7 years, 54% male, and 13% overweight (BMI z-score: + 1 to + 2 standard deviation [SD]). Sixty-five participants (22%) were vaccinated against HAV. Overall, 84/300 participants (28%) demonstrated HAV seropositivity, of whom 55/65 (85%) and 29/235 (12%) were among vaccinated and unvaccinated participants (P < 0.001), respectively. Previous HAV vaccination (adjusted odds ratio [aOR] 47.2; 95% CI 20.0-111.8) and overweight (aOR 4.4; 95% CI 1.7-11.3, compared with normal weight [BMI z-score: - 2 to + 1 SD]) were significantly associated with seropositivity of HAV. In the stratified analyses, crowded bedroom (aOR 3.2; 95% CI 1.3-7.8, per one person increase) and overweight (aOR 5.0; 95% CI 1.8-13.7) were factors associated with HAV seropositivity among vaccinated and unvaccinated participants, respectively. Seroprevalence of HAV antibodies in healthy Thai children and adolescents was relatively low. Recommendation of HAV vaccination for these populations, particularly those with high-risk conditions, should be considered.

A Three-Year Follow-Up of Bone Density Among Thai Adolescents With Perinatally Acquired HIV After Completion of Vitamin D and Calcium Supplementation.

PURPOSE: To determine changes in bone mineral density (BMD) and bone metabolism-related biomarkers among Thai adolescents with perinatally acquired HIV infection (PHIVA) at 3 years following completion of vitamin D and calcium (VitD/Cal) supplementation. METHODS: An observational follow-up study was conducted among PHIVA who received 48-week VitD/Cal supplementation (either high-dose [3,200 IU/1,200 mg daily] or standard-dose [400 IU/1,200 mg daily]). Lumbar spine BMD (LSBMD) was assessed by dual-energy x-ray absorptiometry. Serum 25-hydroxyvitamin D, intact parathyroid hormone, and bone turnover markers were measured. Changes in LSBMD z-scores and other bone parameters at 3 years after stopping VitD/Cal supplementation compared with baseline or week 48 of supplementation were assessed among participants previously receiving high-dose and standard-dose VitD/Cal supplementation. RESULTS: Of 114 enrolled PHIVA, 46% and 54% had previously received high-dose and standard-dose VitD/Cal supplementation, respectively. The median age was 20 years; 53% were male. At 3 years after completion of VitD/Cal supplementation, we observed a significant decline in 25-hydroxyvitamin D and increase in intact parathyroid hormone but no significant rebounds of C-terminal telopeptides of collagen type I and procollagen type I amino-terminal propeptides and no significant changes in LSBMD z-scores among PHIVA in both treatment groups, compared with the measurements at week 48 of supplementation. Notably, LSBMD z-scores at 3 years after stopping VitD/Cal supplements were not significantly altered from baseline evaluations in both PHIVA groups. DISCUSSION: Three years after completion of high-dose or standard-dose VitD/Cal supplementation, LSBMD z-scores of our Thai PHIVA were not significantly changed from baseline and week 48 of supplementation. VitD/Cal supplementation of PHIVA during periods of peak bone mass accrual may have sustained and long-term skeletal benefits.

Comparison of Immunogenicity and Reactogenicity of Five Primary Series of COVID-19 Vaccine Regimens against Circulating SARS-CoV-2 Variants of Concern among Healthy Thai Populations.

To compare immunogenicity and reactogenicity of five COVID-19 vaccine regimens against wild-type SARS-CoV-2 and variants of concern (VoCs) among Thai populations, a prospective cohort study was conducted among healthy participants aged ≥18 years who had never been infected with COVID-19 and were scheduled to get one of the five primary series of COVID-19 vaccine regimens, including CoronaVac/CoronaVac, AZD1222/AZD1222, CoronaVac/AZD1222, AZD1222/BNT162b2, and BNT162b2/BNT162b2. Anti-receptor binding domain (anti-RBD-WT) IgG and neutralizing antibody (NAb-WT) against wild-type SARS-CoV-2 were measured at pre-prime, post-prime, and post-boost visits. NAb against VoCs (NAb-Alpha, NAb-Beta, NAb-Delta, and NAb-Omicron) were assessed at the post-boost visit. Adverse events (AEs) following vaccination were recorded. A total of 901 participants (CoronaVac/CoronaVac: 332, AZD1222/AZD1222: 221, CoronaVac/AZD1222: 110, AZD1222/BNT162b2: 128, and BNT162b2/BNT162b2: 110) were enrolled. Anti-RBD-WT IgG and NAb-WT levels increased substantially after each vaccine dose. At the post-boost visit, BNT162b2/BNT162b2 induced the highest GMC of anti-RBD-WT IgG level (1698 BAU/mL), whereas AZD1222/BNT162b2 induced the highest median NAb-WT level (99% inhibition). NAb levels against VoCs, particularly the Omicron strain, were markedly attenuated for all vaccine regimens (p < 0.001). Overall, no serious AEs following vaccination were observed. All five primary series of COVID-19 vaccine regimens were well-tolerated and elicited robust antibody responses against wild-type SARS-CoV-2 but had attenuated responses against VoCs, particularly the Omicron strain, among healthy Thai populations.