Moderna more effective than Pfizer in direct comparison against the Delta variant

Posted on Aug 18, 2021

The Moderna vaccine outperformed Pfizer/BioNTech in protection against the Delta variant in an observational study released as a preprint this week.

The study compared effectiveness of the two vaccines over the period of January to July 2021, in which the Alpha and Delta were prevalent. 

Both vaccines’ effectiveness was reduced by the Delta variant but Pfizer/BioNTech had a more pronounced reduction. Moderna was 76% effective against infection with Delta in comparison to Pfizer/BioNTech’s 42% effectiveness. 

Furthermore, it found that Moderna conferred a two-fold risk reduction against breakthrough infection compared to Pfizer/BioNTech. Notably there was no difference in ICU admissions and no deaths recorded in the vaccinated population. 

For more information or if you have specific data requests, contact the team at

Document Library