Vaccines Are Less Effective Against Delta—And Pfizer’s Protection Wanes Rapidly—But Are The Best Way To Protect Against Covid, Large Study Finds

While vaccination is still the best way to protect against the delta variant, preliminary research from scientists at the University of Oxford found the shots to be less protective against infection and to lose effectiveness rapidly in the months following vaccination, adding weight to calls to administer booster shots even as many countries have barely begun their vaccination campaigns. 

The team compared the effectiveness of shots made by AstraZeneca, Pfizer and Moderna against alpha and delta variants, the two most recent dominant strains in the U.S. and U.K., using test results from...