Funny you ask. My 4 year old son has this transit, in the 6th house. He has running nose, his immunity is just slightly weaker. We make him drink a lot of water. Psychologically you probably won’t see any effects (such as wanting to be alone, or a depression) until after age of 7 or even 14. I can see also that their guardians may become little more authoritative, just when they actually need to be gentler :)
During this time they can openly blame you for what they perceive as wrong in their lives, while adults would internalize and suppress it, at least for a while.
T Saturn opp mooon in aries in adults usually presents financial shortages, low emotional ebb. So a child may feel the parents frustrations subconsciously, but like others have mentioned, a lot depends on the age of the child/s
Also a lot depends on how natal moon is mathamatically aspected (like any transit) they simply act as background influences. so when they make do a transit it sets off the natal aspects for good or bad.