Moderna may be superior to Pfizer against Delta; breakthrough odds rise with time

  The mRNA vaccine from Pfizer and BioNTech may be less effective than Moderna's against the Delta variant of the coronavirus, according to two reports posted on medRxiv on Sunday ahead of peer review. In a study of more than 50,000 patients in the Mayo Clinic Health System https://bit.ly/37Btmhf, researchers found the effectiveness of Moderna's vaccine against infection had dropped to 76% in July - when the Delta variant was predominant - from 86% in early 2021.