There are three other bits of emerging Covid science that vaccine teams are keeping a close eye on – two encouraging and one a bit terrifying. On the bright side, the virus itself seems stable with no major mutations yet recorded which would derail vaccine development. And the focus of nearly all vaccine teams on disrupting the virus’s ‘spike protein’ looks correct, with more and more research showing its importance.

On the dark side, there is a “nagging concern” that the worst cases of Covid-19 could actually be linked to T-cells generated by the common cold, adds Dr Edwards. A review in Nature described this as the risk of ‘original antigenic sin’, where the presence of T cells triggers an inferior immune response that actually makes the disease worse.

“There’s no indication that this is the case, but it’s just possible that some vaccine candidates will trigger an immune response that makes the virus more severe”, said Dr Edwards. “You just need to look at dengue fever… there are four types, and you almost always have a more severe disease after the second infection”. Let’s hope Covid does not take after dengue.