From factory to syringe, the world’s most promising coronavirus vaccine candidates need non-stop sterile refrigeration to stay potent and safe, notes AP.

But despite enormous strides in equipping developing countries to maintain the vaccine “cold chain,” nearly three billion of the world’s 7.8bn people live where temperature-controlled storage is insufficient for an immunisation campaign to bring Covid-19 under control.

The result: Poor people around the world who were among the hardest hit by the virus pandemic are also likely to be the last to recover from it.