Double-blind, Randomized, Placebo-controlled Study Evaluating Efficacy and Safety of IgPro20 in Post-COVID-19 POTS

Inclusion Criteria: 1. Provide written informed consent and be willing and, in the opinion of the investigator, able to adhere to all protocol requirements. 2. Males and females aged ≥ 18 at the time of providing written informed consent. 3. Diagnosis of post-COVID POTS, defined by both a preceding COVID-19 infection based on confirmed historical documentation and onset of POTS symptoms developing within 4 months after COVID-19 infection as defined per consensus criteria. 4. COMPASS-31 score of at least 40 at the Screening visit. 5. Positive confirmatory standardized standing test (ie, HR increase of ≥ 30 bpm \[≥ 40 bpm for participants aged 18 to 19 years\] within 10 minutes in the absence of orthostatic hypotension) at the Screening visit. Exclusion Criteria: 1. Treatment with Immunoglobulin G (IgG) or plasmapheresis within 12 weeks before Screening 2. Symptoms and / or diagnosis of or receiving treatment for POTS before COVID-19 infection 3. Prior diagnosis of or receiving current treatment at Screening for the following conditions (unless onset was related to the inciting POTS-associated COVID-19 infection): certain neurologic, autoimmune, endocrine, cardiac, or other disorders, and pre-existing psychiatric disorders 4. Presence of active infections, including human immunodeficiency virus infection, hepatitis B, hepatitis C, active SARS-CoV-2 infection, or any uncontrolled systemic infection