The first two years of life, including the period from conception to 2 years of age, are very important for a child’s growth and development. This study sought to describe the developmental status and the environmental factors that influence it in children aged 6 months to 2 years in urban and rural areas. The research sites were purposively selected: specific health centres in the city of Bandung and West Bandung district were chosen and the study was conducted from November to December 2022. A cross-sectional study was conducted with healthy children aged 6 months to 2 years and their parents, who agreed to participate in the study. Researchers performed developmental tests using the Developmental Pre-screening Questionnaire with classifications for normal developmental test results and developmental delays. During the study, 346 children met the inclusion criteria, resulting in a sample of 164 (47.4%) boys and 182 (52.6%) girls. There were no significant differences among children with developmental delays in urban and rural areas. The factors that influence the possibility of developmental delays in the two research areas were the child’s age, exposure to screen time, stimulation, nutritional status, and the use of the mother–child handbook.

Background: Hand, foot, and mouth disease (HFMD) is an infectious disease that often affects children under 5 years of age. Over the past 20 years, enterovirus 71 (EV71) has become a major concern among children, especially in the Asia-Pacific region. Currently, there are no data showing the seroprevalence of HMFDs in Indonesia. This study aimed to determine the seroprevalence of antibodies to EV71 infection in rural and urban areas. Methods: This study was an observational analysis and cross-sectional seroprevalence survey of HFMD in children aged 6 to 71 months. The sampling locations were the Padalarang health centre, which is rural, and the Garuda health centre, which is urban. The total sample included 600 children aged 6–71 months from these two locations. Blood sample testing uses enzyme-linked immunosorbent assays (ELISAs) to identify subjects who are positive for IgG EV71 and the risk factors that may influence it. Results: In total, 596 subjects (99.3%) were positive for the seroprevalence of EV71 IgG in rural and urban areas. Child age, sex, nutritional status, height/age, immunisation status, parental income, and father’s and mother’s educations were not statistically related in rural and urban areas (p > 0.05) because the rate of IgG EV71 seropositivity was very high. Conclusion: This study revealed that the rate of IgG EV71 HFMD seropositivity in Indonesia, especially in the Padalarang health centre and Garuda health centre, was very high. Further research is needed to investigate HFMD cases because of the lack of attention given to this disease and the need to consider whether immunisation is necessary to prevent HFMD. Trial registration: This study is registered at clinicaltrials.gov, National Clinical Trial (NCT) No. NCT05637229.

According to the WHO target product profile for COVID-19 vaccines, the vaccine in development should be indicated for active immunisation in all populations. Therefore, PT Bio Farma developed a candidate vaccine in a subunit protein recombinant platform to help overcome the issue. This trial was an observer-blind, randomised, prospective intervention study. This study targeted individuals who had received complete primary doses of the authorised/approved COVID-19 vaccine. The groups were divided into the primary inactivated vaccine (CoronaVac^®) group, the primary viral vector vaccine (ChAdOx1) group, and the primary mRNA vaccine (BNT162b2) group that received the recombinant protein (IndoVac^®). The groups were compared with the control and primary mRNA vaccine (BNT162b2). The participants enrolled in the study were from two primary care centres in Bandung City and three primary care centres in Denpasar City. A total of 696 participants were enrolled from 1 September to 31 October 2022. The demographic characteristics of the all-vaccine group showed a uniform distribution. The results showed that, compared with the control, the investigational product had inferior effectiveness 14 days after the booster dose was administered. However, 28 days after the booster dose, the investigational product exhibited non-inferior effectiveness compared with the primary groups that received CoronaVac^® (GMR 0.76 (0.57–0.99)) and ChAdOx1 (GMR 0.72 (0.56–59.93)), but the BNT162b2 group (GMR 0.61 (0.39–0.94)) was inferior to the control. At 12 months follow-up after the booster dose, three serious adverse events (SAEs) were reported in three participants, with causality not correlated with the investigated products. Neither AEs of special interest nor severe COVID-19 cases were reported throughout the follow-up period; thus, the IndoVac^® vaccine as a booster was immunogenic and safe. Until the 6-month follow-up after the booster dose, the IndoVac^® vaccine was well tolerated and all reported AEs resolved. This vaccine is registered and can be included in the immunisation programme.

Introduction: Hepatitis B virus (HBV) infection is a global health problem. Anti-hepatitis B surface antigen (HBsAg) levels increase along with vitamin D levels in adults. However, few studies have examined this relationship in adolescents. Few studies have examined the relationship between vitamin D and HBsAg antibody levels, especially in Indonesia. Methods: This cross-sectional study examined vitamin D and anti-HBsAg levels before and after hepatitis B immunisation. All subjects blood was taken to check for vitamin D level. This study was part of the Safety and Preliminary of Immunogenicity Following Recombinant Hepatitis B (Bio Farma) Vaccine in Adults and Children Phase I trial. Results: This study found that 25-hydroxyvitamin D [25(OH)D] status was primarily deficient based on endocrine criteria. The children’s hepatitis B antibody response was mostly < 10 mIU/mL before and ≥ 10 mIU/mL after vaccination. There was a relationship between sex and 25(OH)D status, with median 25(OH)D levels higher in females (18.2 ng/mL) than in males (9.8 ng/mL). However, the relationship between vitamin 25(OH)D status and anti-HBsAg levels pre- and post-vaccination was not significant. Discussion: However, some research found that vitamin D supplementation after immunisation did not impact vaccine response, several studies have reported that vitamin D can decrease HBV replication through various mechanisms, including reducing viral transcription and interfering with viral protein synthesis. Conclusion: There was no relationship between 25(OH)D status and anti-HBsAg levels. Further research is needed to elucidate the underlying mechanisms and establish optimal treatment strategies.

Introduction: Childhood stunting remains a major public health challenge in low- and middle-income countries (LMICs). Inadequate water, sanitation, and hygiene (WASH) conditions contribute to recurrent infections and chronic undernutrition; however, evidence regarding which specific WASH components most strongly influence stunting remains inconsistent. This study aimed to systematically evaluate the association between WASH practices and childhood stunting in LMICs. Methods: We conducted a systematic review and meta-analysis following PRISMA 2020 guidelines. PubMed, Scopus, Web of Science, Cochrane Library, Epistemonikos, EBSCOhost, and Google Scholar were searched up to July 2025. Observational studies from LMICs assessing associations between WASH practices and childhood stunting were included. Study quality was evaluated using the Newcastle–Ottawa Scale. Random-effects meta-analyses were used to pool odds ratios (ORs) with 95% confidence intervals, with publication bias and sensitivity analyses performed. Results: Sixteen studies involving 36,574 children were included. Improved water quality (OR = 0.39; 95% CI: 0.18–0.87) and water accessibility (OR = 0.69; 95% CI: 0.49–0.98) were significantly associated with lower odds of stunting, whereas drinking water source and household water treatment were not. Among sanitation indicators, improved sanitation facility type (OR = 0.71; 95% CI: 0.53–0.94) and environmental sanitation (OR = 0.05; 95% CI: 0.00–0.64) were significantly associated with lower odds of stunting, while toilet access, safe disposal of child feces, and garbage disposal showed no consistent associations. Hygiene practices were also associated with lower odds of stunting, particularly hand hygiene (OR = 0.54; 95% CI: 0.30–0.98) and family hygiene (OR = 0.40; 95% CI: 0.21–0.74), whereas general hygiene was not significantly associated with stunting. Substantial heterogeneity was observed across several outcomes. Conclusions: Several WASH components were associated with lower odds of childhood stunting in LMICs, with more consistent evidence for drinking water quality, water accessibility, and sanitation facility type. Findings for other components were inconsistent. Given substantial heterogeneity and the observational nature of included studies, these results should be interpreted cautiously, and further research is needed to establish causal relationships. Trial registration: PROSPERO CRD420251145998.

Satisfying the needs of the national immunization program requires maintaining diphtheria–tetanus–pertussis (DTP)–hepatitis B (HB)–Haemophilus influenza B (Hib) production. Therefore, new hepatitis B sources are needed. This study aimed to evaluate the immunogenicity of the DTP–HB–Hib vaccine (Bio Farma) that used a different source of hepatitis B. A prospective randomized, double-blind, bridging study was conducted. Subjects were divided into two groups with different batch numbers. Healthy infants 6–11 weeks of age at enrollment were immunized with three doses of the DTP–HB–Hib vaccine after a birth dose of hepatitis B vaccine. Blood samples were obtained prior to vaccination and 28 days after the third dose. Adverse events were recorded until 28 days after each dose. Of the 220 subjects, 205 (93.2%) completed the study protocol. The proportion of infants with anti-diphtheria and anti-tetanus titers ≥ 0.01 IU/mL was 100%, with anti-HBsAg titers ≥ 10 mIU/mL was 100%, and with Polyribosylribitol Phosphate-Tetanus Conjugate (PRP-TT) titers > 0.15 µg/mL was 96.1%. The pertussis response rate was 84.9%. No serious adverse events related to the study vaccine occurred. The three-dose DTP–HB–Hib vaccine (Bio Farma) is immunogenic, well tolerated, and suitable to replace licensed-equivalent vaccines.