Purpose: Simple virilizing congenital adrenal hyperplasia (SV-CAH) due to 21-hydroxylase deficiency (21-OHD) is an autosomal recessive disease caused by pathogenic variants of the CYP21A2 gene. Children with SV-CAH often experience delayed diagnosis, presenting with pseudo-precocious puberty in males and genital virilization in females. Genotyping is essential for diagnosis, treatment, optimization, and phenotype prediction. This study describes the clinical and genetic characteristics of SV-CAH to guide treatment strategies. Methods: From November 2016 to March 2023, 79 children (accounting for 34.3% of 230 CAH cases in the overall children’s cohort) from 75 families were classified as SV-CAH due to 21-OHD at the Vietnam National Children's Hospital. Forty-three children underwent CYP21A2 mutation analysis using multiplex ligation-dependent probe amplification and complete gene sequencing to detect pathogenic variants. Results: Median age at diagnosis was 4.5 years (interquartile range, 1 day–22.3 years). There were 38.0% males and 62.0% females. The most common symptoms were penile enlargement in males (53.3%) and clitoromegaly (87.8%) in females; the height standard deviation (SD) at diagnosis was 1.90±1.79 SD (-2.02 to 5.43) according to the World Health Organization; and bone age advancement was 4.65±2.59 years. Genetic analysis identified 21 pathogenic variants and 22 genotypes in 43 children. The most common variant was p.I173N (47.7%); the most common genotype was p.I173N/p.I173N (16.3%). Conclusion Children with SV-CAH are often diagnosed late. To avoid that, early genetic analysis should be prioritized, especially for children diagnosed through newborn screening programs. Determining the genotype is crucial for optimizing treatment strategies, ensuring personalized management, and avoiding overtreatment.

Purpose: Although some immune protection from close contact with individuals who have coronavirus disease 2019 (COVID-19) has been documented, there is limited data on the seroprevalence of antibodies against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in individuals who were in lockdown with confirmed COVID-19 cases. This study investigated immunogenicity against SARS-CoV-2 in household members and people who lived near home-quarantined patients with COVID-19. Materials and Methods: This cross-sectional study was conducted during the community-based care that took place during lockdowns in District 10, Ho Chi Minh City, Vietnam from July to September 2021. SARS-CoV-2 antibody levels were determined in index cases of COVID-19, household contacts, and a no-contact group from the same area. Results: A total of 770 participants were included (355 index cases, 103 household contacts, and 312 no contacts). All index cases were unvaccinated, but >90% of individuals in the household and no-contact groups had received ≥1 vaccine dose. SARS-CoV-2 neutralizing antibodies (Nabs) were present in >77% of unvaccinated index cases versus 64%/65.4% in the householdo-contact groups (p=0.001). Antibody concentrations in unvaccinated index cases were significantly higher than those in household contacts and no contacts, with no difference between the latter groups. In all cases, antibody levels declined markedly ≥6 weeks after infection, and failed to persist beyond this time in the household and no-contact groups. Conclusion Community-based care may have helped to create community immunogenicity, but Nabs did not persist, highlighting a need for vaccination for all individuals before, or from 6 weeks after, infection with SARS-CoV-2.

Objectives: Tuberculosis (TB) and drug-resistant TB (DR-TB) are national health burdens in Vietnam. In this study, we investigated the prevalence of rifampicin (RIF) and/or isoniazid (isonicotinic acid hydrazide, INH) resistance in patients with suspected TB, and applied appropriate techniques to help rapidly target DR-TB. Methods: In total, 1,547 clinical specimens were collected and cultured using the BACTEC MGIT system (Becton Dickinson and Co.). A resazurin microtiter assay (REMA) was used to determine the proportions of RIF and/or INH resistance. A real-time polymerase chain reaction panel with TaqMan probes was employed to identify the mutations of rpoB and katG associated with DR-TB in clinical isolates. Genotyping of the identified mutations was also performed. Results: A total of 468 Mycobacterium tuberculosis isolates were identified using the REMA. Of these isolates, 106 (22.6%) were found to be resistant to 1 or both antibiotics. Of the resistant isolates, 74 isolates (69.8%) were resistant to isoniazid (INH) only, while 1 isolate (0.94%) was resistant to RIF only. Notably, 31 isolates (29.24%) were resistant to both antibiotics. Of the 41 phenotypically INH-resistant isolates, 19 (46.3%) had the Ser315Thr mutation. There were 8 different rpoB mutations in 22 (68.8%) of the RIF-resistant isolates. The most frequently detected mutations were at codons 531 (37.5%), 526 (18.8%), and 516 (6.3%). Conclusion To help prevent new cases of DR-TB in Vietnam, it is crucial to gain a comprehensive understanding of the genotypic DR-TB isolates.