Johnson & Johnson plans to begin what would be the largest, late-stage trial testing a potential coronavirus vaccine in September, the company confirmed Thursday.
The phase three trial would enroll up to 60,000 healthy people ages 18 and older across nearly 180 locations in the U.S. and other countries, according to a J&J spokesman and ClinicalTrials.gov.
Participants will be randomly selected to receive a dose of the potential vaccine or a placebo, according to details of the trial, which will determine whether the vaccine is safe and effective. They will be followed by researchers for more than two years.
"Our Phase 3 program is intended to be as robust as possible, could include up to 60,000 participants and will be conducted in places with high incidence rates," J&J spokesman Jake Sargent said in a statement to CNBC. "We are using epidemiology and modeling data to predict and plan where our studies should take place and expect that to be finalized soon."
J&J is one of several companies in a race to develop a potential vaccine for Covid-19, which has infected more than 22.4 million people worldwide and killed at least 788,500, according to data compiled by Johns Hopkins University.
There are more than 160 vaccines under development worldwide as of Thursday, according to the World Health Organization, with at least 30 already in clinical trials.
Public health officials and infectious disease experts say world leaders will need an array of drugs and vaccines to defeat the virus, which emerged more than seven months ago.
J&J's trial would be the largest testing a coronavirus vaccine yet. Drug companies Moderna and Pfizer, which both began late-stage trials for their potential coronavirus vaccines last month, said they would enroll around 30,000 participants.
J&J said it is using the same technologies it used to make its experimental Ebola vaccine, which was provided to people in the Democratic Republic of Congo in late 2019. It involves combing genetic material from the coronavirus with a modified adenovirus that is known to cause common colds in humans.
The U.S. Department of Health and Human Services announced on Aug. 5 that it reached a deal with Janssen, J&J's pharmaceutical subsidiary, worth approximately $1 billion for 100 million doses of its vaccine. The deal gives the federal government the option to order an additional 200 million doses, according to the announcement.
The company has previously said it could produce 600 million to 900 million doses by April if the vaccine works well.
J&J anticipates possible vaccine batches for potential emergency use available in early 2021, the company told CNBC Thursday.