A Study to Evaluate Safety, Tolerability, Pharmacokinetics, and Pharmacodynamics of BIIB133 (Dapirolizumab Pegol) in Healthy Japanese and Caucasian Participants

Key Inclusion Criteria:

• Negative polymerase chain reaction (PCR) test result for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) within 14 days of Day -1 (inclusive).
• Japanese study participant has both biological parents and all 4 grandparents of Japanese descent and, if living outside of Japan for more than 5 years, must maintain a Japanese diet.
• Caucasian study participant has both biological parents and all 4 grandparents of Caucasian descent.
• Have a body weight between 50 and 90 kilograms (kg) (inclusive) and body mass index (BMI) between 18.0 and 26.0 kilograms per meter square (kg/m^2) (inclusive) at the Screening Visit.

Key Exclusion Criteria:

• History of any clinically significant cardiac, endocrine, gastrointestinal, hematologic, hepatic, immunologic, metabolic, urologic, pulmonary, neurologic, dermatologic, psychiatric, or renal disease, or other major disease, as determined by the Investigator.
• Have undergone major surgery in the last 6 months or plans to undergo elective major surgery during the study period.
• Have a known hypersensitivity to any components or excipients of DZP including polyethylene glycol (PEG).
• Have received any prescription or nonprescription medicines including over-the-counter remedies and herbal and dietary supplements within 14 days or 5 half-lives of the respective drug, whichever is longer, other than acetaminophen and antihistamines.
• Current enrollment in any other drug, biological, device, or clinical study, or treatment with an investigational drug or approved therapy for investigational use within 30 days prior to Day -1, or 5 half-lives, whichever is longer.
• History of chronic, recurrent, or recent (within 6 months prior to Screening) severe infection and/or at risk for severe infection, as determined by the Investigator.
• Have symptoms consistent with SARS-CoV-2 infection, per the judgement of the Investigator, within 14 days prior to Day -1, including but not limited to fever (temperature > 37.5 degree Celsius [°C]), sore throat, new and persistent cough, breathlessness, or loss of taste or smell.
• Have close contact within 14 days prior to Day -1 with a SARS-CoV-2 (+) individual. Close contact is defined as (1) being within 6 feet of an infected individual (as confirmed via laboratory assessment) for at least 15 minutes within 2 days of symptom onset or (2) being within 6 feet of an asymptomatic infected individual for at least 15 minutes within 2 days of that asymptomatic individual undergoing specimen collection for SARS-CoV-2 testing.
• Clinically significant abnormal laboratory test result values, as determined by the Investigator, at Screening or Day -1.
• Have received any live/attenuated vaccination within 6 weeks prior to Visit 2 (Day 1) or plans to receive any live/attenuated vaccination within 120 days after the dose of study treatment.

NOTE: Other protocol defined Inclusion/Exclusion criteria may apply.