Much of what makes the coronavirus pandemic scary is how much we don’t know. We don’t know how long we’ll be forced to stay indoors. We don’t know if social distancing is working . We don’t know when a vaccine will be available. And we don’t even know exactly what the symptoms look like. As many as 50% of people with COVID-19 remain asymptomatic . Some sufferers report enduring what felt like a mild cold, while others are dying alone in hospitals on ventilators.