Seroprevalence of mumps among children and adolescents in Thailand, 2020.

Thailand has implemented single-dose mumps-containing vaccines since 1997 and two doses since 2010. This study aimed to describe the seroprevalence of mumps among children who received one- or two-dose mumps vaccines. A cross-sectional study of 145 children (aged 3-9 years) and 422 adolescents (10-18 years) was conducted. Mumps IgG seropositivity was defined as ≥ 22 RU/mL by EUROIMMUN ELISA method. The mumps seroprevalence was higher in children (82.1%, 95% CI 74.8-87.9) compared to adolescents (41.7%, 95% CI 37.0-46.6) who had received at least one dose of the mumps vaccine. Among those receiving 2 doses of mumps vaccine at ≥ 5 years after their last mumps vaccination, only 51.3% had maintained IgG ≥ 22 RU/ml. There was a reverse correlation between mumps IgG titer and the time interval from the second dose of mumps vaccine (R = -0.44, p < 0.001). A booster dose of MMR vaccine in young adults may be needed.

High seroprevalence of rubella in Thai children with a 2-dose MMR national immunization policy.

Rubella is generally a mild disease, but infection during pregnancy can cause congenital rubella syndrome. Thailand has implemented a two-dose MMR vaccination policy since 2010. This study aimed to describe the seroprevalence rate of rubella among children and adolescents in Thailand. We conducted a cross-sectional study of 132 healthy children (aged 3-9 years) who had received 2 doses of rubella vaccine and 424 adolescents (aged 10-18 years) who were expected to receive at least 1 dose of rubella vaccine. Stored serum samples from healthy children and recently drawn serum samples from adolescents were tested for rubella IgG antibody using a commercial enzyme-linked immunosorbent assay (ELISA) kit (EUROIMMUN). Seroprotection was defined as a rubella IgG level ≥ 10 IU/mL. The rubella seroprevalence rate among children and adolescents who had 2 documented doses of MMR was 97.0% (95 %CI 92.5-99.2%) and 85.4% (95% CI 78.8-90.6%, p < 0.01) respectively. The geometric mean titer of rubella was higher in children, 38.3 (95% CI 33.5-43.9) compared to adolescents, 22.5 (19.4-25.9) IU/mL. We observed an inverse correlation between the rubella titer and time interval from the second rubella containing vaccine dose (R = -0.30, p < 0.01). A 2-dose MMR vaccination course produces a high seroprevalence of rubella immunity in children, which decreases with time, suggesting waning of immunity. Thai clinical trials registry number TCTR20191120001.

Acceptability of blood-based HIV self-testing among adolescents aged 15-19 years at risk of HIV acquisition in Bangkok.

INTRODUCTION: Young men who have sex with men (YMSM) and young transgender women (YTGW) in Thailand are at high HIV risk. HIV self-tests (HIVSTs) are rapidly administrable and prompt linkage to HIV treatment or prevention services. This study assesses the acceptability and feasibility of blood-based HIVST use in adolescents. METHODS: A cross-sectional study was conducted among YMSM and YTGW aged 15-19 years with HIV acquisition risk. Participants completed questionnaires on the HIVST and then administered INSTI® independently, an HIVST immunoassay detecting gp41 and gp36 antibodies from finger-stick blood. Confirmatory HIV antibody tests were performed. RESULTS: Between July and September 2020, 90 adolescents were enrolled. Mean (SD) age was 17.6 (1.1) years. Half (N = 45) were YMSM. Forty-six (51%) were first-time HIV testers, and 32 (36%) had "ever used" HIV pre-exposure prophylaxis (PrEP). Two (2.2%, 95% CI: 0.0-5.3) tested positive, 21 (23.4%) invalid, and 67 (74.4%) negative. Invalidity causes included 17 (81%) insufficient blood, 3 (14%) buffer spillage, and 1 (5%) procedural missteps; all had negative HIV antibody tests. HIV self-test acceptability was 87.8% (95% CI: 81.0-94.5). Most (79%) preferred HIVST performance in hospital rather than at home. CONCLUSIONS: HIVSTs are acceptable in HIV at-risk adolescents. Blood-based HIVSTs should be positioned as rapid point-of-care tests with real-time linkage to HIV services.