The main purpose of this study is to evaluate the safety and tolerability of single and multiple ascending doses of RO7806881 in healthy participants.

Inclusion Criteria:

• Participants must be males or females who are overtly healthy as determined by medical evaluation
• Participants must have body weight (BW) ≥ 40 kilograms (kg) and body mass index (BMI) within the range 18-32 kilograms per square meter (kg/m^2) (inclusive)

Exclusion Criteria:

• Pregnancy, breastfeeding, or intention to become pregnant during the study or within 6 months after the final dose of study treatment
• History of any clinically significant autoimmune, gastrointestinal, renal, hepatic, pulmonary, neurological, psychiatric, cardiovascular, endocrinological, hematological, or allergic disease; metabolic disorder; cancer or cirrhosis
• Latent tuberculosis (TB) or potentially active TB
• Any major illness within 1 month before the screening examination or any febrile illness within 1 week prior to the screening visit and up to first dose administration
• Concomitant disease or condition that could interfere with, or treatment of which might interfere with, the conduct of the study, or that would, in the opinion of the Investigator, pose an unacceptable risk to the participant in this study
• History of hypersensitivity to biologic agents or any of the excipients in the formulation, or other allergy that contraindicates participation in the study
• Live vaccines within 1 month of the first screening visit or during the screening period
• Non-live vaccines within 2 weeks prior to dosing
• Previous exposure to RO7806881
• Positive hepatitis C virus (HCV) antibody test result
• Positive test results for hepatitis B infection
• Positive human immunodeficiency virus (HIV) antibody test result
• Positive test result consistent with cytomegalovirus (CMV) or epstein-barr virus (EBV)