Vaccines like to be kept cool, none more so than the Pfizer candidate for Covid-19, which has to be deep-frozen. And that's going to be an issue for developing countries -- and for rural areas in the ...

A man in a lab coat carries a box of dry ice - Eder Paisan/Shutterstock Dry ice is the solid form of carbon dioxide and the perfect trick to keeping ice cream frozen in your cooler thanks to it being ...