Unlike other candidates, however, major US trials have focused on its effectiveness as a single dose. If proved successful, single-dose Janssen jabs would accelerate the speed of roll-out, while protecting people from coronavirus in a matter of weeks.
The vaccine is currently going through final data examination and should be filing for approval from US, European and UK regulators in early February. Johnson & Johnson has said it is ready to ship doses from its factories in Europe as soon as it gets the green light.
In November, scientists launched a trial involving around 30,000 people globally including 6,000 people in the UK to observe the effects of spacing out the Janssen jab in two doses, which may help the vaccine work even better and last longer.
Professor Saul Faust, director of the NIHR Southampton Clinical Research Facility and the chief investigator leading the trial, said: “We are really hopeful of good results from the single dose trial. Johnson & Johnson are a large drug company, experienced at making vaccines, who know how to make and transport vaccines at pace and scale, if it works.”
He added: “We need all the vaccines, and it might well be that one dose will be approved by the regulators for emergency use.
“But we don’t know yet. And we won’t know until the trials are done.”