I have a four month old son who got
RSV along with the whole household in early February. We live at altitude (7200) feet, but the baby did well--- one night of observation in the hospital, where his O2 sats were 96-97 when he was being held or was upright, but would fall when sleeping or laying down into the mid-80s. So, he went on oxygen.
Two months later he is still failing every overnight oxygen study in order to get him off nighttime oxygen.