|Study||Study design||Population||Risk factors|
|PICNIC||Prospective||Infants hospitalized for RSV infections||(i) Underlying disease (CHD, CLD, immunodeficiency, multiple congenital malformations).|
(ii) Postnatal age <6 weeks.
(iii) GA 33–35 weeks.
|FLIP||Prospective case-control study||Preterm born at 33–35 weeks’ GA (risk factors for RSV-related hospitalization)||(i) Chronologic age ≤ 10 weeks at the beginning of RSV epidemic season.|
(ii) Breastfeeding ≤ 2 months.
(iii) ≥1 school-age siblings.
(iv) ≥4 residents or visitors at home.
(v) Family history of wheezing.
|Multicenter Italian birth cohort||Multicenter prospective cohort study||Infants born at 33 weeks’ GA or more||(i) GA 33 + 0–37 + 6 weeks|
(ii) No breastfeeding.
(iii) Presence of siblings.
(iv) Maternal smoking.
(v) Family history of atopy or wheezing.