My babies had it. It's part of the programme in the US, where they were born. They were born end of November, winter time (we lived in the Midwest), and got it at 2, 4 and 6 months, so basically over the winter. Rotavirus is very dangerous (not life threatening) to babies and every year thousands of babies end up in the hospital because of rota (mainly severe dehydration). My children had no side effects, a little runny poo maybe once (it's a living virus) but other than that none. Recommend it although it depends on the circumstances. For us with brutal cold winters, etc. it was an easy decision.