Answering the question can seem to be a simple matter of adding up the costs and benefits resulting from the measures. But things are a lot more complicated than that. What counts as a benefit or a cost is far from obvious. Even if we agreed to what they were, finding a common measure to compare them is riddled with objections. Ultimately, no algorithm can tell us whether the policies were worth it, it’s all down to human judgement writes Stephen John.

According to some analysts, a year of lockdown measures cost the UK economy £251billion. Was it worth it? You might think that the 251billion figure is too high or too low. Maybe the true cost was "only" £25billion. Still, would that have been a price worth paying? These aren't just questions for future historians. Rather, as worries around vaccine effectiveness against new variants grow and previously untouched countries go into lockdown, policy-makers around the world need to decide: when is the cure worse than the disease?

There's a way of thinking about the question, central to health economics, thrown around in debates around the pandemic: that we should adopt lockdown policies only when their benefits outweigh their costs. This answer is simple and appealing. Unfortunately, it's also false. Or, at least, it's an answer which hides far more than it illuminates. While it may be tempting to think that there must be some number - lying, say, between 25.1million and 251trillion - at which the costs of lockdown outweigh the benefits, this is an illusion.