Final answer:
An SAE must be reported to the FDA within 15 calendar days when it is an unexpected serious and fatal drug event after a drug's NDA approval. Sponsors are required to report these events, and the FDA also receives voluntary reports from consumers and health professionals through MedWatch.
Step-by-step explanation:
An SAE (Serious Adverse Event) must be reported to the FDA within 15 calendar days if it is an unexpected serious and fatal adverse drug event. After NDA (New Drug Application) approval, the sponsor is obligated to review and report every adverse drug experience known to them. These reportable events are a subset of adverse events that are serious in nature, which include events that are life-threatening, lead to hospitalization or prolongation of hospitalization, result in persistent disability or incapacity, or are a congenital anomaly/birth defect.
The FDA also allows health professionals and consumers to submit voluntary reports of adverse drug events through the MedWatch program, which are known as 'spontaneous reports'. While spontaneous reports are voluntary, the mandatory 15-day reports by sponsors are crucial for the FDA's ongoing post-marketing safety surveillance of approved drugs.