When calculating a child's age to choose the correct age interval, does the date administered count as a complete day in the calculation?

Yes, the administration date is counted as a full day when calculating age. But, the child's birth date is not counted. For example, if a child is born 5/20/2018, then on 5/20/2019 the child's age is 1 year, 0 days. For easy age calculation, use the online ASQ Calculator or download the free ASQ Calculator app from the app store.