Safety, Tolerability, and Pharmacokinetics of MK-1654 in Infants (MK-1654-002)

Inclusion Criteria:

- is healthy, based on screening safety laboratory, medical history, and physical
examination results

- is a pre-term infant (born at 29 weeks to 35 weeks gestational age [inclusive]) or a
full-term infant (born at over 35 weeks gestational age), as confirmed in medical
records

- weighs ≥2 kg at screening

Exclusion Criteria:

- has been recommended to receive palivizumab per local standard of care

- has ≥1 documented out-of-range safety laboratory results (adjusted for age)

- has a known hypersensitivity to any component of the respiratory syncytial virus (RSV)
monoclonal antibody

- has a history of congenital or acquired immunodeficiency (e.g., splenomegaly)

- has documented human immunodeficiency virus (HIV) infection, hepatitis B (HBsAg
positive), or hepatitis C (HCV ribonucleic acid [RNA] positive)

- has known history of functional or anatomic asplenia

- has a diagnosis of failure to thrive within 14 days of screening

- has known or history of a coagulation disorder contraindicating intramuscular
injection

- has received or is expected to receive blood products (except irradiated platelets)
within 3 months prior to enrollment

- has prior known documented RSV infection

- has hemodynamically significant congenital heart disease

- has chronic lung disease of prematurity requiring ongoing medical therapy

- has a history or current evidence of any condition, therapy, lab abnormality or other
circumstance that, in the opinion of the investigator, might expose the participant to
undue risk by participating in the study, confound the results of the study, or
interfere with the participant's participation for the full duration of the study

- has any history of malignancy prior to randomization

- if any of the following apply, the Day 1 visit may be rescheduled for a time when
these criteria are not met:

- has had a recent febrile illness (rectal temperature 38.1°C [100.5°F] or higher or
axillary temperature 37.8°C [100.0°F] or higher) within 72 hours pre-dose

- is not up-to-date on required vaccinations per local pediatric vaccine schedule at
time of screening

- has received inactivated or component vaccines (eg, influenza, hepatitis B) less than
14 days pre-dose

- has received live, attenuated, non-study licensed pediatric vaccines (e.g., Bacillus
Calmette-Guerin vaccine) less than 30 days pre-dose

- has received any prior vaccine or monoclonal antibody (mAb) for the prevention of RSV

- is currently participating in or has participated in an interventional clinical study
with an investigational compound or device at any time prior to first dose
administration or while participating in this current study (participants enrolled in
observational studies may be included and will be reviewed on a case-by-case basis for
approval by the Sponsor)

- has enrolled previously in this study and been discontinued

- participant's mother participated in a RSV vaccine clinical study while pregnant and
participant is ≤3 months of chronological age

- is unable to provide blood sample at screening

- cannot be adequately followed for safety according to the protocol plan

- has a parent/legally acceptable representative who is unlikely to adhere to study
procedures, keep appointments, or is planning to relocate during the study

- is, or has, an immediate family member (eg, spouse, parent/guardian, sibling, or
child) who is directly involved with the study at the site or with the Sponsor