 As the coronavirus spreads across the U.S., nobody knows how many people will be infected. But judging from prior pandemics, some experts suggest that between 20 and 60 percent of adults will contract the virus. Not everyone who gets infected is tested or shows symptoms. Harvard's models estimate that on average, about a fifth of those infected would have symptoms that require hospitalization. ProPublica reviewed new data from the Harvard Global Health Institute to map several scenarios for how this pandemic could play out. The colors show the hospital beds available in each region, starting with green, where hospitals would be less than 100 percent full. To red, where at least twice as many hospital beds would be required than are currently available. This assumes that hospitals don't free up already occupied beds. Even in one of the best-case scenarios where the virus spreads over 12 months and the infection rate is 20 percent, many regions of the country would be at or above their existing hospital bed capacity. Some regions would struggle more than others to handle surges of patients. One place is Seattle, the region that had the nation's first virus-related deaths. Typically, about 71 percent of Seattle's hospital beds are occupied, leaving less than a third of their beds open for additional patients. If 20 percent of adults become infected within six months, the region would need more than double its total beds. If the virus spreads more slowly over 12 or 18 months, the pressure for additional hospital beds eases. But if the infection rate in Seattle is 40 percent, the need for beds goes up dramatically. And if it's 60 percent over six months, people would need about five times as many hospital beds. If the virus spreads faster and a greater percentage of people are infected, bed shortages would be more dire. If 20 percent of the country is infected over six months, most regions would need more hospital beds than are currently available. Hospitals would be forced to either expand capacity, limit elective surgeries and unnecessary treatments, or even make life-and-death decisions about rationing care. In the worst-case scenario, with a 60 percent infection rate in just six months, the nation would require more than seven times the number of hospital beds that it currently has available. That's why slowing the spread over a longer period of time is critical. Experts say if we adopt social distancing strategies like staying home and avoiding crowds, we can slow the spread so hospital staff can be better prepared to treat patients in the coming months.