The first big real-world study of the Pfizer/BioNTech vaccine to be independently reviewed shows the shot is highly effective at preventing Covid-19, in a potential landmark moment for countries desperate to end lockdowns and reopen economies.

Up until now, most data on the efficacy of Covid-19 vaccines has come under controlled conditions in clinical trials, leaving an element of uncertainty over how results would translate into the real world with its unpredictable variables...