Moderna’s vaccine efficacy held strong, did not wane after 5 months, new study shows
In a study of more than 30,000 participants, the vaccine remained safe and effective for an average of 5.3 months after their second shot. Even after the time had passed, the shot was 93.2% effective in preventing illness from COVID-19, and 98.2% effective in preventing severe disease.

https://www.nytimes.com/2021/09/22/health/covid-moderna-pfizer-vaccines.html

Research published on Friday by the Centers for Disease Control and Prevention found that the efficacy of the Pfizer-BioNTech vaccine against hospitalization fell from 91 percent to 77 percent after a four-month period following the second shot. The Moderna vaccine showed no decline over the same period.

Moderna’s efficacy against severe illness in those studies ranged from 92 to 100 percent. Pfizer-BioNTech’s numbers trailed by 10 to 15 percentage points.