"The safety profile and immunogenicity after only a single dose are supportive for further clinical development of [vaccine] Ad26.COV2.S at a dose level of 5x1010 vp, as a potentially protective vaccine against COVID-19," the report said on Friday. "A single dose of Ad26.COV2.S elicited strong humoral responses in the vast majority of vaccine recipients."
The Johnson and Johnson vaccine is the fourth in the United States to enter a final phase of clinical trials.
US President Donald Trump has promised that 100 million doses of a vaccine will be distributed throughout the United States by the end of the year. Trump earlier claimed that a vaccine could be available for distribution in the US before the 3 November presidential election.
Many Democrats have accused Trump of trying to fast-track the vaccine approval process, sidestepping scientifically approved methods, in order to get one delivered ahead of the election.