RSV research study shot?

Has anyone been offered to do a RSV research study shot? My doctor offered it to me and I guess it is supposed to build up antibodies for your baby so they won’t get RSV. But I’m skeptical on doing it. My son had bronchitis twice under 3 months and it was so hard to go through. The shot IS a study so had not been tested but I guess around 200 women in our area did it with no side affects at all happened during her pregnancy and after labor, their babies tested positive for RSV but were asymptomatic showing zero signs. I’m a little scared and don’t really know what to do! Let me know your thoughts