This study is two arms, opening parallel-designed, observational study. Diarrheal and infectious episodes, including acute upper and lower respiratory infections (ARI), changes in stool patterns, use of systemic antibiotics, adverse events and study formula consumption will be compared in children 2 - 3 years of age who are assigned to receive one of the two following study formulas for a 3-month feeding period: a2 growing up stage 3 formula puls lactoferrin supplement and Enfinitas growingup stage 3 formula.~200 children eligible for the study will be enrolled from two study sites and randomly assigned to two groups to feed for 90 days. About 160 children (80 for each group) are expected to finish the study, and data of primary and secondary outcomes will be collected during the four visits across the study. A sample size of 80 completed per group is needed to achieve a 80% power.~The Andersen-Gill model will be used to model the primary outcome (recurrent event of either diarrheal disease or an acute respiratory infection) under the framework of the proportional hazard assumption. For other secondary outcomes such as duration of acute respiratory infections(ARI) and/or diarrheal disease, episodes of systemic antibiotic use,amount of study formula consumed,changes in stool pattern and cost of treatment will also be analyzed.
The goal of this observational study is to compare the incidence of ARI and/or diarrheal disease associated with feeding different formulas with and without lactoferrin supplement in children of 2-3 years old. 200 children eligible for the study will be enrolled from two study sites and randomly assigned to two groups (a2 growing up stage 3 formula puls lactoferrin supplement, and Enfinitas growing up stage 3 formula) to feed for 90 days. About 160 children (80 for each group) are expected to finish the study, and data will be collected during the four visits across the study.~Researchers will compare the two groups to see if there is significant decrease of the occurrence of diarrheal disease and/or acute respiratory infection for children fed with a2 growing up stage 3 formula puls lactoferrin supplement