The United States Food and Drug Administration has authorised the use of the Johnson & Johnson coronavirus vaccine in adults. Maureen Ferran, a virologist at the Rochester Institute of Technology, explains how this third authorised vaccine works and explores the differences between it and the Moderna and Pfizer–BioNTech vaccines that are already in use.
How does it work?
The Johnson & Johnson vaccine is what is called a viral vector vaccine.
To create this vaccine, the Johnson & Johnson team took a harmless adenovirus – the viral vector – and replaced a small piece of its genetic instructions with coronavirus genes for the SARS-CoV-2 spike protein.
After this modified adenovirus is injected into someone’s arm, it enters the person’s cells. The cells then read the genetic instructions needed to make the spike protein and the vaccinated cells make and present the spike protein on their own surface. The person’s immune system then notices these foreign proteins and…