Inclusion Criteria:  It is important to carefully consider whether a subject is suitable for enrollment into this observational study. Fulfillment of the inclusion and exclusion criteria for each subject will be documented by a qualified member of the investigative staff before any subject is enrolled.  Healthy infants who fulfill all the following inclusion criteria will be included:  Having obtained his/her parents' (or his/her legally accepted representative's [LAR's]) written informed consent and having evidence of personally signed and dated informed consent document indicating that the subject's parents/LAR have been informed of all pertinent aspects of the study. Subject's parent(s)/LAR is of legal age of consent, is willing and able to fulfill the requirements of the study protocol.  For group 1, healthy infants aged ≤ 10 days after birth (date of birth = Day 0).  For group 2, healthy infants with maximum age of 6 months  Full-term gestational birth (≥ 37 and ≤ 42 weeks). Subject's parent(s)/LAR is able to be contacted directly by telephone throughout the study. Both parents registered have a fixed work and / or residence within their jurisdiction.  Exclusion Criteria:  Complicated pregnancy (e.g., preeclampsia, gestational diabetes, bowel disease) as assessed by medical interview/ medical record when available Infant's parents/LAR not willing and/or not able to comply with scheduled visits and the requirements of the study protocol Currently participating or having participated in another clinical trial within 4 weeks prior to trial start.