We bring you up to speed on the science behind the most urgent questions about the virus and the disease. We demystify the research and help you understand what it really means. I'm Tanya Lewis. I'm Josh fishman. And we're scientific Americans senior health editors. Today we'll explain the new official methods to determine if you're in a pandemic safe zone or danger area. Then we'll discuss what other pandemics look like when they were ending and whether this one at long last is heading down a similar path. The map of the U.S. shifted last week, or at least the map of COVID danger did. Suddenly, a lot of hazardous regions were deemed safer. What happened, Josh, did COVID disappear? It was a weird moment, Tanya, and no COVID hasn't gone away. But last Friday morning, people looked at an official Centers for Disease Control map showing much of the nation was in a high risk area, and the next day that map showed about 60% of the U.S. was really at low or medium risk. And people in those areas didn't need to wear a mask anymore. The agency said. What happened was three things. One, now we have more tools to keep people safer, such as vaccinations, and new antiviral drugs. We are seeing fewer infections as we slide down from the scary omicron wave, though about 2000 Americans are still dying every day, and none of us should tolerate that level of death. And three, because of the first two, the CDC decided to recalculate how it measured COVID risk. That's what changed the map. In the old scheme, the agency used only case counts in a particular county, 100 cases or more per 100,000 meant high risk of virus transmission, and the CDC said people in those places should wear masks. The new scheme shifts the calculation to measures of severe disease. It emphasizes the number of new hospital admissions and how much of a hospital is filled with existing COVID patients..