COVID-19 is a highly contagious, potentially deadly disease. By the spring of 2020 it had already infected more than 4 million people worldwide, causing more than 285,000 deaths. Virtually every country on earth reported cases. For the better part of 2020, the disease caused entire countries to all but shut down.

A danger to all -- The pandemic spreads across the globe -- Life under the lockdown -- Struggling workers and businesses -- Schools close their doors -- Hospitals and health care workers fight the pandemic -- The federal government's response to COVID-19 -- Emerging from the pandemic.