A head-to-head study of all three authorized coronavirus vaccines in the United States finds the Moderna vaccine is slightly more effective than Pfizer's in real-life use in keeping people out of the hospital, and Johnson & Johnson's Janssen vaccine comes in third, but still provides 71% protection.

Pfizer's vaccine provided 88% protection against hospitalization, and Moderna's was 93% effective.
The US Centers for Disease Control and Prevention led a nationwide study of vaccination involving more than 3,600 adults hospitalized for Covid-19 between March and August.

"Among U.S. adults without immunocompromising conditions, vaccine effectiveness against COVID-19 hospitalization during March 11- August 15, 2021, was higher for the Moderna vaccine (93%) than the Pfizer-BioNTech vaccine (88%) and the Janssen vaccine (71%)," the team wrote in the CDC's weekly report on death and disease, the MMWR.

"Although these real-world data suggest some variation in levels of protection by the vaccine, all FDA-approved or authorized COVID-19 vaccines provide substantial protection against COVID-19 hospitalization."

They found that the biggest difference between the vaccine made by Moderna and Pfizer/BioNtech's vaccine was driven by a decline that started about four months after people were fully vaccinated with Pfizer's vaccine.
"Differences in vaccine effectiveness between the Moderna and Pfizer-BioNTech vaccine might be due to higher mRNA content in the Moderna vaccine, differences in timing between doses (3 weeks for Pfizer-BioNTech versus 4 weeks for Moderna), or possible differences between groups that received each vaccine that were not accounted for in the analysis," the team wrote.