Cameroon and Sierra Leone use solar-powered fridges to keep vaccines and other temperature-sensitive medicines stable. Combined with battery storage, they stay cool even when there is no sun or alternative power supply. Some freeze water into an ice lining, meaning they do not even need batteries. Supplied to the Democratic Republic of Congo during the covid-19 pandemic, they can now be used for mpox vaccines. When it comes to keeping people cool with limited or no air-conditioning, building design is essential, particularly in dense cities. Nearly 60% of Africans will probably live in cities by the end of the decade. Around 70% of the buildings that are likely to exist on the continent by 2040 have yet to be built, according to the UN.