In March 2020, the World Health Organization officially classified Covid-19, the disease caused by the novel coronavirus, as a pandemic. That means the disease no longer constitutes just an outbreak or even an epidemic; the coronavirus has now spread around the world, and will continue to reach into other countries and communities. That’s in part because of how contagious the virus is. When you’re infected with the flu, it takes about two days before you start to show symptoms. But coronavirus symptoms take an average of five to six days to appear, so it’s easy to spread well before you notice that you’re feeling sick. Many people are spreading it while going about their daily lives as usual. The risk is that once coronavirus starts to spread in a community, about 20% of cases are severe and may require hospitalization. As those cases multiply, hospitals can fill up quickly. And people with severe cases of COVID-19 who can’t receive proper medical attention are at a much higher risk of dying. Ideally, we would be able to stop the virus from spreading entirely. We can’t do that right now. What we can do is slow it down, so that the severe cases get spread out over a longer period of time, and hospitals are less likely to be overwhelmed on any given day. And that’s where each one of us comes in. The best way to slow down the spread is for everyone — healthy, sick, young, old — to limit social contact as much as possible, immediately. This is called social distancing, and it only works if enough of us do it. But if we do, it could mean the difference between the life and death of someone you know.