A Study to Evaluate Safety, Tolerability and Pharmacokinetics of Two Different Doses of Alpha1-Proteinase Inhibitor Subcutaneous (Human) 15% in Participants With Alpha1-Antitrypsin Deficiency

Inclusion Criteria: * Have a diagnosis of congenital Alpha1-antitrypsin deficiency (AATD) with an allelic combination of ZZ, SZ, Z(null), (null)(null), S(null), or "at-risk" alleles (subjects with "at-risk" alleles must be individually evaluated for eligibility by the Medical Monitor). * Have a documented pre-Alpha1-Proteinase Inhibitor (PI) augmentation therapy serum alpha-1 antitrypsin (AAT) level \<11 micrometer (μM) (80 milligrams per decilitre (mg/dL) if measured by radial immunodiffusion or 50 mg/dL if measured by nephelometry). * Subjects may be naïve to Alpha1-PI augmentation therapy or may be currently receiving Alpha1-PI augmentation therapy or received Alpha1-PI augmentation therapy within the past. If the subject is currently receiving Alpha1-PI augmentation therapy of any kind, he/she must be willing to discontinue that treatment for at least 25 days prior to the Week 1 (Baseline) Visit and remain off any kind of Alpha1-PI treatment, other than the IPs for this study, while participating in the study. * At the Screening Visit, have a post-bronchodilator forced expiratory volume (FEV1) ≥30% and \<80% of predicted and FEV1/forced vital capacity (FVC) \<70% (Global Initiative for Chronic Obstructive Lung Disease (GOLD) stage II or III). Exclusion Criteria: * Have had a moderate or severe Chronic obstructive pulmonary disease (COPD) exacerbation during the 4 weeks before the Week 1 (Baseline) Visit. * Have history of lung or liver transplant. * Have any lung surge…