Did lockdowns save lives? We will never have a definitive answer to this vital question because it was impossible to conduct controlled experiments — we don’t have two identical countries, one where lockdown was imposed and one where it wasn’t. Nor is it easy to compare similar countries, for the simple reason that every country in the world — bar Comoros in the Indian Ocean — reacted to Covid by introducing at least one non-pharmaceutical intervention (NPI) by the end of March 2020.