The effectiveness of Pfizer/BioNTech, Moderna, and Johnson & Johnson COVID-19 vaccines declined considerably as the Delta variant became dominant in the United States, reported a study of nearly 800,000 veterans.

Published in the journal Science, the study suggested that the three vaccines provided about the same protection against the virus in March, but it changed 6 months later. The Moderna vaccine was 89% effective in March, and it declined to 58% effectiveness in September. The Pfizer/BioNTech vaccine went from being 87% effective to 45% effective over the same duration. The Johnson & Johnson vaccine exhibited the biggest decline, from being 86% effective to 13% effective over the same period. The three vaccines lost the effectiveness in the ability to protect against death in veterans aged 65 years and above after only 3 months… (Medscape)