J&J begins final-stage trial of its single-shot COVID-19 vaccine

Washington: Johnson & Johnson started giving its experimental coronavirus vaccine to a huge group of volunteers on Wednesday, marking the final stage of testing for the shot.

J&J, the world's largest healthcare company, is the fourth US-backed program to start these pivotal studies, called phase-three trials. The company is looking to give the shot to 60,000 volunteers around the world, and said we could know whether it works as soon as December.

J&J's vaccine joins experimental shots developed by Moderna, Pfizer and BioNTech, and AstraZeneca and the University of Oxford in beginning the final stage of development.

Unlike these other vaccines, J&J's trial will test a single dose. The other three shots are being tested as a two-dose regimen, with a pair of injections given a few weeks apart.

The $381 billion healthcare giant started early-stage human trials in July in the US and Belgium. While results have not been published from those studies, J&J Chief Scientific Officer Paul Stoffels said the results were positive and encouraging. Stoffels said data would be published within the next two days.

"We are convinced that a single-dose can be very efficacious," Stoffels said, adding J&J also plans to eventually start another late-stage trial that will test a two-dose regimen.

Dr. Anthony Fauci, the nation's top infectious-disease expert, said results from J&J's trial will likely lag a month or two behind studies that got started earlier. Fauci said he anticipates data from phase-three trials that started in July or August, like Moderna's and Pfizer's, to come in November or December.

Fauci leads the National Institutes of Health's infectious disease division, which is helping pay for the trial along with J&J and the US Biomedical Advanced Research and Development Authority.

Fauci estimated that J&J's data would likely come around December or January, while emphasizing that there's uncertainty in when these studies will deliver results. Vaccine studies don't necessarily deliver results after a pre-set length of time. Instead, the timeline depends on how many people get sick with the coronavirus over the course of the trial.

J&J's chief scientist echoed Fauci's timeline.

"We hope to see an endpoint around the end of year or early next year," Stoffels said.

The trial is recruiting volunteers in countries including the US, South Africa, Brazil, Argentina, Columbia, and Chile, he said.