J&J COVID-19 vaccine shows success in interim analysis of Phase III trial

An interim analysis of Phase III clinical trial data has shown that the investigational COVID-19 vaccine developed by Janssen Pharmaceuticals, a division of Johnson & Johnson (J&J), appears to be safe and effective at preventing moderate and severe COVID-19 in adults.

The vaccine, called Ad.26.COV2.S or JNJ-78436725, requires only a single injection and can be stored in a refrigerator for months.

The interim analysis, part of the ENSEMBLE trial, assessed 468 cases of symptomatic COVID-19 among 44,325 adult volunteers in Argentina, Brazil, Chile, Colombia, Mexico, Peru, South Africa and the US. The investigational inoculation was reportedly 66 percent effective at preventing the study’s combined endpoints of moderate and severe COVID-19 at 28 days post-vaccination among all volunteers, including those infected with an emerging viral variant.

The ENSEMBLE trial, which began in September 2020, is being conducted as part of the federal COVID-19 response.

Geographically, the level of protection for the combined endpoints of moderate and severe disease varied: 72 percent in the US; 66 percent in Latin American countries; and 57 percent in South Africa, 28 days post-vaccination. The prophylactic was reportedly 85 percent effective in preventing severe/critical COVID-19 across all geographical regions. 

No deaths related to COVID-19 were reported in the vaccine group, while five deaths in the placebo group were related to COVID-19. Overall, there were 16 deaths in the placebo group and three deaths in the vaccine group.

The Janssen vaccine is a recombinant vector vaccine that uses a human adenovirus to express the SARS-CoV-2 Spike (S) protein. The adenovirus vector used in the experimental vaccine has been modified, so that it can no longer replicate in humans and cause illness.

Unlike the two COVID-19 vaccines currently authorised by the US Food and Drug Administration (FDA) for emergency use (Pfizer and Moderna), the Janssen investigational vaccine requires only a single vaccination.