design: Mothers of study participants were trained to collect the fecal samples and provided with mobile cards for timely communication with the collection team in the field. The mothers collected the fecal sample and sent an immediate message to the field team to pick up the sample within 30 minutes. Overall, four samples were collected from each child: one sample at nine months to capture microbiota at the pre-intervention stage, while three samples were collected at twelve, thirteen, and eighteen months to evaluate post-intervention taxa (Figure 1B). Fresh samples were transferred into a pre-chilled cryovial, snapped to the aluminum cryo cone and placed into a freezing container (Coleman) at 2 to 8C. The time taken from the passage of fresh stools to being snap-frozen in a dry shipper was less than 30 minutes. The Coleman was carried in liquid nitrogen dry shipper to the local laboratory and later shifted to IDRL, AKU on dry ice where samples were stored at -80C until shipped to BGI Genomics (formerly Beijing Genomics Institute). A 30ng qualified DNA template was tested for sample integrity by agarose gel electrophoresis and concentration by a microplate reader (Qubit fluorometer). The quantified samples (6 -100ng/uL) were normalized to 30ng DNA per reaction. fusion primers were designed to include Illumina adapter sequences, an 8-nucleotide index sequence, and a gene-specific primer and added to the Polymerase chain reaction (PCR) reaction system. All PCR products were purified by Agencourt AMPure XP beads, dissolved in an Elution Buffer, and labeled for library construction. Library size and concentration were detected by Agilent 2100 Bioanalyzer. Qualified libraries were sequenced pair-end on the HiSeq 2500 platform according to their insert size.