We have a covid-19 vaccine that works. But can we keep it cold enough to get it to enough people? Among Pfizer and BioNTech’s long list of risks and uncertainties for its BNT162b2 vaccine , which this week was reported to be 90 per cent effective , is the challenge of its “ultra-low temperature formulation”, and how to store and distribute it along the so-called “cold chain”.

Between manufacture and doses …