“The first thing you have to do is define success, but that’s not as easy as you might think. You can’t just look at how often people with COVID in a given country went on to die from it. That statistic will be skewed by the fact that older people are more likely to die from COVID than younger people, so countries with especially old populations will almost inevitably look worse. (One country that did particularly well—even though it has the world’s oldest population—is Japan. It had the best compliance with mask mandates of any country, which helps explain some of its success, but other factors were probably also at play.)”