NEW JERSEY (REUTERS) - Johnson & Johnson said on Thursday (Dec 17) that it has enrolled about 45,000 participants for the first late-stage trial of its Covid-19 single-dose vaccine candidate and that it expects interim data by late-January.

The company, however, is lagging behind rivals Pfizer Inc and Moderna Inc in the race for a vaccine to combat the Covid-19 pandemic that has infected about 75 million people globally.

J&J's study, named Ensemble, is being conducted by its unit Janssen, the drugmaker said in a statement.

While seven countries have already authorised the emergency use of Pfizer and German firm BioNTech's candidates, Moderna's rival vaccine was set for regulatory authorisation this week in the United States.

J&J also said it plans to submit an emergency use authorisation application to the US Food and Drug Administration (FDA) in February if the data from the study is safe and effective.

The company had earlier this month announced cuts in enrollment for the vaccine trial from its original plan for 60,000, as higher rates of Covid-19 infections amid a worsening pandemic should generate the data it needs with fewer study subjects.

The Ensemble trial was paused for over a week in October after a patient developed an "unexplained illness" during the study.

The company later said it would resume the trial after an evaluation found no clear cause for the illness.

A separate late-stage clinical trial of an investigational Covid-19 vaccine candidate by Janssen to explore a two-dose regimen was ongoing, J&J said.