COVIDIG (COVID-19 Hyper-ImmunoGlobulin)

Inclusion Criteria: * The COVID-19 patient who diagnosed by PCR within 3 days prior to randomized And who is hospitalized with COVID-19 related symptoms * The subject who has symptoms of COVID-19 within 7 days * The subject with pneumonia confirmed by imaging diagnosis related to COVID-19 OR a 70-year-old or older OR 60-year-old or older with underlying disease (diabetes or hypertension or obesity or smoker) * Willing and able to provide written informed consent prior to performing study procedures Exclusion Criteria: * asymptomatic patient * The subject who requiring mechanical ventilation or ECMO * The subject who are underlying oxygen therapy before affected by COVID-19 * The subject who have received antiviral drugs for other disease within 4 weeks * History of allergy to IVIG or plasma products * The subject who received IVIG or convalescent plasma from a person who recovered from COVID-19 * IgA deficiency * Cretinine \> 2 X ULN * The subject with a history of thrombosis or high risk of thromboembolism * The subject with reduced heart function \[NYHA (New York Heart Association) Functional Class III or IV\]; or cerebral cardiovascular disorder or a patient with the medical history (ischemic disease, cardiovascular disease, cerebrovascular disorder, blood vessel disorder, etc.)