I think that a lot infant studies do not really take breastfeeding and particularly exclusive breastfeeding in the early months into account due to the relatively small number of babies who don't receive any formula. I would think disruption to gut flora alone could be a significant factor in morbidity rates. (I'm going off on a tangent, I realise.)
We skipped the rotavirus for DD as I didn't think it was worth the risk to her gut given how unlikely it was for an exclusively breastfed baby to get the virus. I wish I had also skipped for DS.

I hope your DS is feeling better today LnB and your day is a good one