Experts welcome 'extremely encouraging' Covid-19 vaccine results 

A vaccine, developed by the Johnson & Johnson-owned pharmaceutical firm, is 66% effective overall at preventing moderate to severe coronavirus 28 days after vaccination

Janssen’s new single-shot Covid-19 vaccine was found to be 66% effective (Jane Barlow/PA)

Scientists have welcomed the “extremely encouraging” results of Janssen’s new single-shot Covid-19 vaccine trial announced less than 24 hours after the Novavax jab also appeared effective.

The vaccine, developed by the Johnson & Johnson-owned pharmaceutical firm, is 66% effective overall at preventing moderate to severe coronavirus 28 days after vaccination, trial results show.