The Oxford-AstraZeneca Vaccine Approval May Be the Most Globally Important Yet

The COVID-19 vaccine developed by the University of Oxford and AstraZeneca wasn’t the first to be OK’d by regulators in the U.K.—health officials authorized the Pfizer-BioNTech jab nearly four weeks earlier. And it’s not the most effective—Stage 3 clinical trials suggest it prevents COVID-19 symptoms about 70% of the time vs. about 95% for the Pfizer vaccine and a similar one from Moderna (which is authorized in the U.S., but not the U.K.).

But the greenlight from the British Medicines and Healthcare Products Regulatory Agency on Wednesday could be a...