In June of 2019 the CDC audited Fort Detrick. They subsequently issued a report detailing their findings. The report indicates 2 breaches of toxins occurred.
On June 30, 2019, a respiratory illness led to the death of 3 people and sickness of 63 people including staff at a senior living center located about 60 miles from Ft Detrick. The cause could not be identified. Story from ABC News here.
July 2019, a second assisted living facility is reporting 25 cases of a mystery respiratory illness. This is about 54 miles from Fort Detrick.
On July 18, 2019 Fort Detrick is shut down.
September 2019, blood samples from Italians are drawn and subsequently test positive for Covid antibodies. These are the earliest human samples that have tested positive for Covid.
December 13, 2019 through January 17, 2020 blood samples are collected in the US which would later be tested for Covid antibodies. 1.4% would test positive. Extrapolating this % to the full US population suggests 4.7M people had Covid antibodies at this time.
January 13, 2020, 2 days before China had awareness that Covid was human to human transmissible, the Moderna vaccine is already developed.
Note: May update occasionally as new information comes to light.