A little more than a year ago, the Centers for Disease Control and Prevention urged employers to "increase teleworking options" as cases of the novel coronavirus began to build.

The World Health Organization declared COVID-19 a pandemic weeks later, on March 11, 2020.

As employers pass the one-year mark from initial shutdowns and safety measures, there's much to look back on, from mass transitions to remote work and the nation's first paid leave law to workforce contact tracing and vaccine mandates.

Below, we've gathered our coverage of key moments employers experienced in the past year to form a timeline of sorts. Here are 15 stories that illustrate what HR professionals faced in a year defined by COVID-19.