In a study released last week, the CDC found that Moderna was significantly more effective against hospitalizations and emergency department or urgent care encounters than the Pfizer or J&J vaccines.

While the 3 vaccines were collectively 86% effective in preventing hospitalization, protection was significantly higher among Moderna vaccine recipients (95%) than among those who got Pfizer-BioNTech (80%) or Johnson & Johnson (60%). That finding echoes a smaller study by the Mayo Clinic Health System in August, not yet peer-reviewed, which showed the Moderna vaccine to be more effective than Pfizer-BioNTech at preventing infections during the delta wave.

It raises questions about whether the two vaccines should be treated the same way policy-wise.

"There have been sort of signals from enough separate sources that start to paint a picture that may reflect a real biological phenomenon — a real difference. I’m starting to believe that there’s something underlying it," said Natalie Dean, an Emery professor who specializes in vaccine study design.

The large CDC study that found a significant difference in the vaccines' effectiveness found that Moderna's was higher across all ages.
https://www.cdc.gov/mmwr/volumes/70/wr/mm7037e2.htm?s_cid=mm7037e2_w

https://www.cdc.gov/mmwr/volumes/70/wr/mm7037e3.htm?s_cid=mm7037e3_w


Recent data suggests that Moderna's coronavirus vaccine may maintain a higher effectiveness over time than Pfizer's.