As the Covid crisis has unfolded, infection rates have fluctuated and restrictions have proliferated. But it has always felt that there was one idea to cling to: that by working out which countries were doing well - and which were not - there was something to be learned. After all, historians will surely puzzle over how the countries of Western Europe, with broadly similar economies, produced such drastically different outcomes. So far, at least. We use international comparisons all the time, of course - they're a way of measuring how our own governments are doing. But even comparing the simplest data can be complex. There can be differences in how and when death is reported, how co-morbidities are reflected on death certificates, and for how long after a positive test a death is considered to be Covid-related. All will influence how a country's performance at any given moment is measured. For the moment, the gaps in performance appear to be startling. The death rate in Germany stands at around 11.5 deaths per 100,000 people, while in neighbouring Belgium it's more than seven times higher at 87 per 100,000. France stands somewhere in between at around 48 per 100,000 while the UK is nearer the top of the European table, at 63.3 per 100,000. Each is a prosperous country with a capable health-care system and each has applied broadly similar tools to fight the virus, with some combination of lockdowns, social distancing and the encouragement of improved hand hygiene bolstered by localised curfews in some cities. But the further you look into the data the harder it becomes to explain the differences. Lombardia and Veneto for example are neighbouring provinces in Northern Italy, but the differences between their experiences are striking - Lombardia's death rate is 167 per 100,000 and Veneto's 43. It's perhaps because of the sheer difficulty of explaining the numbers that the view from Germany on whether it is doing better than others is more cautious than you might imagine. One factor, it's acknowledged could be timing - how quickly you take action may be as important as the action you take. The influential German scientist Christian Drosten put it like this ahead of this month's World Health Summit in Berlin: "There are already speeches celebrating German success but it's not very clear where that comes from. We have moved with exactly the same measures as others. We didn't do anything particularly well, we just did it sooner." Germany does have an extensive testing system, a well-established network of public health track and trace officials, and a greater number of places in intensive care units than most other countries. But perhaps equally importantly, it has Angela Merkel - one of the few world leaders who is a scientist and who can understand and explain the data herself. At a news conference after meeting with the heads of Germany's regional governments for example Ms Merkel began one answer with the words: "I simply conducted a model calculation." She proceeded to talk her audience through the maths of exponential growth in a pandemic, concluding with a warning that Germany would need to take extra measures. She was careful to describe the situation as "urgent" but not dramatic. Christian Drosten says a population that feels well-informed is more likely to comply with government instructions or requests. As he put it: "I'm reading about support rates of 85-90%, that's a huge accomplishment…everyone knows someone in their own circle who doesn't accept the measures but it's possible to talk to them and that's what we should be doing. I think this is one of the biggest advantages we have in Germany."Prof Drosten's point is about where science meets society - in other words it's not about the nature of the tools in the toolbox but how the country reacts when the government gets the tools out. We raised this point with Prof Yves Van Laethem, an advisor to the government of Belgium, who said it was possible his government had confused its public by changing messages too quickly and too often.