Studies show Human Milk Oligosaccharides (HMOs) influence on infant growth were conflicted. This study aims to determine the relationship between HMO profiles and weight growth indicators of infants ages 0-4 months in Indonesia. A prospective longitudinal study was conducted among 120 mother-infant pairs aged 0 – 4 months from the hospital and Public Health Center in Jakarta between August 2021 – May 2022. The gene analysis for the Secretor and Lewis status of the mother were performed by using targeted Next Generation Sequencing (NGS) and Sanger at baseline. The HMO profiles (2'FL, LNFP I, LNT, LNnT, 3'SL, and 6'SL), breast milk calories, and fat were examined at 0, 2, and 4 months. Weight for age z-score, weight for length z-score, infection episode, and mother's body mass index were examined every month. Data were analyzed using Pearson or Spearman correlation test (correlation coefficient), general linear model for repeated measures ANOVA test and Friedman test (mean difference between and within groups, respectively) and logistic regression unadjusted OR (association between dependent and independent variables), with a p-value <0.05 considered statistically significant. Infants' weight velocities were higher among high LNT and 3'SL levels in the second month, and in high 2'FL and LNFP I mothers in the fourth month. HMO profile (2’FL, LNFP I, and LNT) of lactating mothers have a positive relationship with weight growth indicators, and innovative interventions to enhance HMO concentration among mothers should be considered as one of the ways to improve infant growth.

Background: Routine childhood vaccination, e.g., for diphtheria-tetanus-pertussis (DTP), might provide an additional protection towards SARS-CoV-2 infection. This concept of heterologous immunity was explored in healthy children receiving both DTP and inactivated SARS-CoV-2 vaccines. Methods: A cross-sectional study was performed on 154 healthy children aged 6–8 years old in Jakarta, Indonesia. Their vaccination status of DTP (including diphtheria-tetanus booster vaccine at 5 years old) and CoronaVac (from 6 years old) were recorded. Peripheral blood samples were collected from all participants, in which anti-diphtheria toxoid IgG, anti-SARS-CoV-2 S-RBD antibodies and T cell-derived IFN-g were measured. Results: Study participants with complete DTP vaccination had significantly higher titer of anti-diphtheria toxoid IgG than the ones without (median=0.9349 versus 0.2113 IU/mL; p<0.0001). Upon stratification based on DTP and CoronaVac vaccination statuses, participants with complete DTP and CoronaVac vaccinations had the highest titer of anti-SARS-CoV-2 S-RBD antibodies (median=1,196 U/mL) and the highest concentration of SARS-CoV-2-specific T cell-derived IFN-g (median=560.9 mIU/mL) among all groups. Conclusion: Healthy children aged 6-8 years old with complete DTP and CoronaVac vaccinations exhibited higher SARS-CoV-2-specific adaptive immune responses, particularly on their T-cell response. This suggests an additional benefit of routine childhood vaccination to generate protection against novel pathogens, presumably via heterologous immunity.