My son was 2 months early last october, and had to have the RSV shot, once a month from october until April 20, he got his last one! They are VERY expensive, closer to $2000, per vile,per baby, per month, and if they get too chubby, they may need two viles which you still pay for all of vile even if they only use a drop out of number 2. I am sure they will give you a pamphlet about it, but from mine it basically states what you probably already know, since they were premature they did not receive all the virus fighters from you, Synagis gives them antibodies to fight for a whole month, hence why they are needed every 28-30 days. There are small side effects, which accompany nearly all meds, examples in this brochure are upper respiratory tract infection, ear infection, fever, and runny nose. Which it is very clear that these are not common, just has happened, so don't fear. In my opinion, this is well worth the money! Knock on wood, but my son has yet to get sick until now, and it is only allergies from all the rain we've had in OK. He is almost nine months old and not even an ear infection, and I only breast fed for two and a half months... He maybe just a healthy baby, but I attribute it to this shot. They told us they may even recommend he take it again this year, which i will not decline if my insurance will allow. Because I have a friend whose daughter contracted RSV and was in ICU on ventilators when she was 6 months old! I'm sure you never wanna go there again! Hopefully I didn't frighten you, and may have provided some help.