The purpose of this study is to evaluate the safety, PK and efficacy comparing Pagibaximab Injection to placebo in preventing staphylococcal sepsis in very low birth weight infants. 1550 infants will be enrolled prior to 48 hours of life and will be randomized 1:1 to receive active drug or placebo on study days 0, 1, 2, 9, 16, and 23.

This is a Phase 2b/3, randomized, double-blind, multicenter, placebo-controlled study evaluating the safety, efficacy and pharmacokinetics (PK) of pagibaximab (100 mg/kg/dose) in comparison to placebo for the prevention of staphylococcal sepsis in VLBW infants (600 -1200 grams). Subjects monitored for treatment related adverse events and tolerability to infusion of study drug. Neonatal sepsis will be assessed in the presence of clinical signs and symptoms and one blood culture positive for S. aureus or two blood cultures positive for Coagulase Negative Staphylococci (CoNS). The study period will be 35 days after the first dose or until, death, discharge, or transfer, whichever occurs first.

• Placebo Comparator: Placebo
• Experimental: Pagibaximab at 100 mg/kg intravenously at Days 0, 1, 2, 9, 16 and 23.

Inclusion Criteria:

1. In-patient at a Neonatal Intensive Care Unit (NICU)
2. Informed consent obtained from the legally authorized representative
3. Less than 48 hours old at the time of first infusion
4. Birth weight between 600 grams and 1200 grams
5. Estimated gestation age ≤33 weeks

For multiple gestations, twins may be enrolled if they each meet the entry criteria. They will both be assigned to the same treatment group.

Exclusion Criteria:

1. Infants with history of a hypersensitivity or severe vasomotor reaction to any antibody preparation.
2. Infants with proven staphylococcal infection prior to randomization.
3. Infants with a concomitant infection or other medical condition, whose participation, in the opinion of the Investigator and/or medical advisor, may create an unacceptable additional risk.
4. Immunodeficiency other than due to prematurity.
5. Currently receiving, recently received, or planned to receive other investigational agents that could interfere with conduct or results of this study.
6. Severe congenital or chromosomal anomaly that would limit life expectancy or required corrective measures during the period of this study
7. Uncontrolled seizures