https://blogs.scientificamerican.com/observations/a-new-web-tool-can-help-you-figure-out-if-those-symptoms-might-be-covid-19/ > On March 12, 2020, the World Health Organization declared the COVID-19 outbreak a pandemic. A pandemic occurs when a new disease, for which people have no immunity, spreads across the globe, being readily transmitted from person to person. In the last century we’ve had four pandemics, all caused by novel strains of flu, the worst being the pandemic of 1918 in which a third of the world’s population became ill and about 675,000 people in the US died. The most recent flu pandemic occurred in 2009. In contrast to previous pandemics, it was considered mild. Yet the CDC recorded over 60 million cases in the US, including 274,000 hospitalizations and over 12,000 deaths. > On March 26, 2020, the Institute of Health Metrics and Evaluation, a group committed to helping policymakers and donors determine how best to help people live longer and healthier lives, presented their first set of estimates predicting use of health services due to COVID-19. They estimated more demand for hospital services than there is capacity to deliver. Health systems have been preparing for weeks in anticipation of a tsunami of patients. Through public health policies aimed at keeping us physically separated (or socially distanced), the acceleration of the outbreak and total number of people sick at any given point in time can be reduced. Hospitals will make more space for patients by decreasing non-COVID related hospital utilization through cancelation of elective surgeries, and by setting up tents in their parking lots.