Johnson & Johnson (J&J) announced on Wednesday that it will decrease the size of its US-based phase 3 trial currently testing its COVID-19 vaccine as cases surge across the country.
According to a source familiar with the matter, the downsizing of the trial is due to the climbing COVID-19 case figures across the US.
As cases grow, participants will be more likely to come into contact with the virus, allowing J&J to evaluate its vaccine in a smaller population of volunteers.
“We continue to anticipate that interim data from the ENSEMBLE trial will be available by the end of January,” J&J said in a statement.
“If the vaccine is safe and effective, an emergency use authorisation application could be submitted to the FDA in February,” the company added.
In a press briefing on Wednesday, US official and head of the government’s Operation Warp Speed initiative Moncef Slaoui mentioned that over 38,000 people have now been recruited into the J&J study.
He added: “With J&J, we decided to cap the recruitment to around 40,000 subjects, which will happen by the end of this week, so in the next two [or] three days.”
J&J advanced its COVID-19 vaccine candidate into phase 3 testing in September following positive interim results from a phase 1/2a clinical study of the shot. The pivotal late-stage study is investigating the safety and efficacy of a single vaccine dose versus placebo in preventing COVID-19.
Interim results from the phase 1/2a ENSEMBLE trial demonstrated that the shot has a promising safety profile and immunogenicity after a single dose.
J&J’s COVID-19 candidate uses the company’s AdVac technology platform, which was also used to develop and manufacture the its existing Ebola vaccine, as well as construct its other investigational candidates for Zika, RSV and HIV.
The company is also collaborating with the UK government on a phase 3 clinical trial in multiple countries which will explore a two-dose regimen of the vaccine.
Pfizer and BioNTech, which have already generated phase 3 results for their COVID-19 shot and won approval in the UK and Canada, included 44,000 participants in late-stage testing of their vaccine.
Moderna, another company which has already scored phase 3 results, tested its COVID-19 vaccine in 30,000 volunteers.
J&J will continue its study until 154 participants within the trial have contracted SARS-CoV-2, the virus which causes COVID-19. Specifically, COVID-19 cases in the J&J trial must be severe or moderate and occur at least two weeks after vaccination to count, according to STAT News.