Bangladesh introduced hepatitis B vaccine in a phased manner during 2003–2005 into the routine childhood vaccination schedule. This study was designed to evaluate the impact of the introduction of hepatitis B vaccine in Bangladesh by comparing hepatitis B surface antigen (HBsAg) prevalence among children born before and after vaccine introduction and to estimate the risk of vertical transmission of chronic hepatitis B virus (HBV) infection from mother to infant. We also evaluated the field sensitivity and specificity of an HBsAg point-of-care test strip. We selected a nationally representative sample of 2,100 prevaccine era and 2,100 vaccine era children. We collected a 5-mL blood sample from each child. One drop of blood was used to perform rapid HBsAg testing. If a child had a positive HBsAg test result with the rapid test, a blood sample was collected from the mother of the HBsAg-positive child and from the mothers of two subsequently enrolled HBsAg-negative children. All samples were tested for serologic markers of HBV infection using standard enzyme-linked immunosorbent assay. One (0.05%) child in the vaccine era group and 27 (1.2%; 95% confidence interval [CI]: 0.8–1.7%) children in the prevaccine era group were HBsAg positive. Mothers of HBsAg-positive children were more likely to be HBsAg positive than mothers of HBsAg-negative children (odds ratios = 4.7; 95% CI: 1.0–21.7%). Sensitivity of the HBsAg rapid test was 91.2% (95% CI: 76.6–98.1%) and specificity was 100% (95% CI: 99.9–100%). The study results suggest that even without a birth dose, the hepatitis B vaccine program in Bangladesh was highly effective in preventing chronic HBV infection among children.

A major obstacle to in-depth investigation of the immune response against Nipah virus (NiV) infection is its rapid progression and high mortality rate. This paper described novel information on the vertical transfer of immune properties. In January 2020, a female aged below five years and her mother from Faridpur district of Bangladesh were infected. Both had a history of raw date palm sap consumption and were diagnosed as confirmed NiV cases. The daughter passed away, and the mother survived with significant residual neurological impairment. She conceived one and a half year later and was under thorough antenatal follow-up by the surveillance authority. A healthy male baby was born. As part of routine survivor follow-up, specimens were collected from the newborn and tested for NiV infection at the reference laboratory to exclude vertical transmission. Although testing negative for anti-Nipah IgM and PCR for NiV, a high titre of anti-Nipah IgG was observed. The transfer of humoral immunity against NiV from mother to neonate was confirmed for the first time. The article will serve as a reference for further exploration regarding NiV-specific antibodies that are transferred through the placenta, their potential to protect newborns, and how this may influence vaccine recommendations.

Background/Objectives: Nipah virus (NiV) is a highly pathogenic zoonotic virus with fatality rates exceeding 70% and causes recurring outbreaks in South and Southeast Asia. Reliable serological assays are critical for outbreak surveillance, diagnosis, and evaluation of vaccine-induced immune responses. This study aimed to develop and qualify an indirect enzyme-linked immunosorbent assay (ELISA) based on recombinant NiV glycoprotein G for the detection of virus-specific IgG antibodies in human serum. Methods: An indirect ELISA was developed and optimized for antigen concentration, blocking conditions, and serum dilution. The assay performance was evaluated using convalescent human sera from Bangladesh, along with the World Health Organization (WHO) International Standard for anti-Nipah virus antibodies, maintained and distributed by the National Institute for Biological Standards and Control (NIBSC). Analytical validation was conducted in accordance with ICH Q2 (R2) guidelines, including assessments of sensitivity, specificity, Precision, Linearity, and detection limits. Results: The assay demonstrated 100% sensitivity and specificity relative to reference sera. Intra-assay coefficients of variation ranged from 0.36% to 5.73%, and inter-assay variation was 4.16%, indicating high precision. The ELISA showed excellent Linearity (R² > 0.995). The lower limit of detection was 0.51 IU/mL, and the lower limit of quantification was 0.98 IU/mL. Conclusions: The developed ELISA is a BSL-2-compatible, robust, and scalable platform suitable for serosurveillance and the assessment of vaccine-induced immunity in endemic regions. Calibration against an international standard supports its applicability for standardized antibody measurement. This assay provides a practical tool for NiV outbreak response and vaccine evaluation.