At the beginning of 2020, as the nation celebrated the start of a new year, many Americans were still unaware of the "mysterious pneumonia" that had sickened dozens of workers at a live animal market in Wuhan, China.

The illness, later identified as the "novel coronavirus", began spreading rapidly across the globe. Several studies have suggested that the virus had already been spreading in the United States, potentially as early as December 2019.

However, it was not until mid-January of 2020, when the virus would officially be recognized as present on U.S. soil.

Two years ago, on Jan. 21, 2020, the Centers for Disease Control and Prevention (CDC) confirmed the first domestic case of coronavirus. The positive patient was a 35-year-old man from Washington state, who had recently returned from Wuhan, China.