Study to Evaluate the Efficacy and Safety of AstroStem-V in Treatment of COVID-19 Pneumonia

Inclusion Criteria: * Adults aged 19 to 80 years at the time of signing the written consent form * Subjects diagnosed with pneumonia by radiologic examination (Chest X-ray or CT) at screening and baseline * subject who has moderate COVID-19 disease: * Subjects have laboratory-confirmed SARS-CoV-2 infection within 28 days from screening by authorized a reverse-transcription polymerase chain reaction (RT-PCR) or equivalent testing at baseline * A subject who has symptoms of moderate illness with COVID-19, which could include any symptom of mild illness or shortness of breath with exertion * A subject who has clinical signs suggestive of moderate illness with COVID-19, such as respiratory rate ≤ 20 breaths per minute, SpO2 ≥ 93% on room air at sea level, heart rate ≤ 90 beats per minute * No clinical signs indicative of severe COVID-19 disease severity * Subjects voluntarily participate in the clinical trial with written informed consent Exclusion Criteria: * Subjects who have pulmonary disease except COVID-19 pneumonia * SpO2 ≤ 93% * Subjects who have uncontrolled shock * Subjects diagnosed with COVID-19 with CPR or requires treatment of Extra Corporeal Membrane Oxygenation (ECMO) * Subjects with an irreversible brain lesion or medical history of malignant tumors * Subjects treated for heart disease within 3 months prior to screening * Subjects who are receiving immunosuppressant therapy for transplantation or who are taking immunosuppressive drugs such as steroids, TNF-alpha inhibitors * Subject treated with stem cells. * Subjects with end-stage renal failure who need renal replacement therapy or cirrhosis patients with complications * Subjects who have an average life expectancy to be less than 2 months due to the underlying disease * Subjects who have history of thromboembolism or pulmonary arterial hypertension * Subjects who currently have positive HIV test results * Pregnant or breast-feeding women * Subjects with pregnancy planned during clinical trials. Women or men of childbearing age who do not agree to maintain contraception by choosing, or who do not agree to use the appropriate method of contraception * suitable contraceptive methods: condom, sponge, foam, gel, diaphragm for contraception, intrauterine device, etc. Periodic abstinence (eg, calendar method, ovulation method, symptom body temperature method, post ovulation method) and restraint is not considered an accepted method of contraception, and hormonal contraceptives are not allowed. However, women having no potential are pregnancy due to menopause (amenorrhea more than 12 months after the last menstruation) or surgical infertility is possible to participate in the study only the pregnancy test is negative * Subjects who administered other investigational products within 12 weeks prior to IP administration * Subject who the principal investigator considers inappropriate for the study due to any other reasons than those listed above * Subjects who cannot tolerate aspirin