A Study to Evaluate the Safety and Efficacy of MEDI8897 for the Prevention of Medically Attended RSV LRTI in Healthy Preterm Infants.

This pivotal Phase 2b study will determine if MEDI8897 will be efficacious in reducing
medically attended RSV-confirmed lower respiratory tract infections (LRTI) in healthy preterm
infants entering their first RSV season. The population to be enrolled is healthy preterm
infants born between 29 weeks 0 days and 34 weeks 6 days gestational age (GA) who would not
receive RSV prophylaxis. A total of 1500 infants will be randomized 2:1 to receive either
MEDI8897 or placebo. Subjects will be followed for 360 days after dosing. Enrollment is
planned at approximately 197 sites across the USA, Canada, Europe, and the Southern
Hemisphere.

Key Inclusion Criteria:

1. Healthy infants born between 29 weeks 0 days and 34 weeks 6 days GA

2. Infants who are entering their first full RSV season at the time of screening

Key Exclusion Criteria:

1. Meets American Academy of Pediatrics (AAP) or other local criteria to receive
commercial palivizumab

2. Any fever (≥ 100.4°F [≥ 38.0°C], regardless of route) or lower respiratory illness
within 7 days prior to randomization

3. Acute illness (defined as the presence of moderate or severe signs and symptoms) at
the time of randomization

4. Active RSV infection (a child with signs/symptoms of respiratory infection must have
negative RSV testing) or known prior history of RSV infection

5. Receipt of palivizumab or other RSV monoclonal antibody or any RSV vaccine, including
maternal RSV vaccination