Washington – A pediatric vaccine for respiratory syncytial virus (RSV),a highly contagious, common respiratory virus that infects the nose, throat, and lungs, is on hold, per US Food and Drug Administration`s instructions. An FDA document shows that a phase 1 trial of two experimental Moderna RSV vaccines in infants aged five to eight months was paused in July as five cases of severe to very severe lower RSV respiratory tract infections were reported among 40 babies who received the vaccine dose, compared with just one case in the placebo group of 20. Five infants required hospitalization, with one needing mechanical ventilation.