The Phase 3 trial will enrol up to 60,000 people aged 18 years and older in the US, Argentina, Brazil, Chile, Colombia, Mexico, Peru and South Africa.
Johnson & Johnson continues to scale up manufacturing capacity to ultimately provide one billion doses a year of its Janssen vaccine candidate. Unlike a number of other frontrunners in the COVID-19 vaccine race, its Phase 3 trial is based on the vaccine requiring a single rather than double shot.
Phase 3 trial
The initiation of the Phase 3 trial – ‘Ensemble’ – follows positive interim results from J&J’s Phase 1/2a clinical study, which demonstrated ‘the safety profile and immunogenicity after a single vaccination were supportive of further development’ (results have been submitted to medRxiv and are due to be published shortly).
Taking place across 215 clinical research sites globally, the Ensemble trial is randomized, double-blind, placebo-controlled clinical trial designed to evaluate the safety and efficacy of a single vaccine dose versus placebo.
It will include ‘significant representation’ of participants aged over 60; as well as representations of populations that have been disproportionately impacted by the pandemic (in the US this includes Black, Hispanic/Latinx, American Indian and Alaskan Native participants). The trial will include those both with and without comorbidities associated with an increased risk for progression to severe COVID-19.
The trial is designed primarily to determine if the investigational vaccine can prevent moderate to severe COVID-19 after a single dose. It also aims to understand if the vaccine can prevent COVID-19 requiring medical intervention and if the vaccine can prevent milder cases of COVID-19 and asymptomatic SARS-CoV-2 infection.
Like fellow COVID-19 vaccine developers Moderna and Pfizer, J&J has released the clinical protocol for its Phase 3 trial.
J&J has also agreed in principle to collaborate with the UK on a separate Phase 3 trial which will explore a two-dose regime.
The Janssen COVID-19 vaccine candidate, JNJ-78436735 (also known as Ad.26.COV2.S), is a recombinant vector vaccine that uses a human adenovirus to express the SARS-CoV-2 spike protein in cells.
It uses the company’s existing AdVac technology platform (used to develop and manufacture Janssen’s European Commission approved Ebola vaccine and construct its Zika, RSV, and HIV vaccine candidates).
The vaccine is estimated to remain stable for two years at -20 °C and at least three months at 2-8° C. This would make the vaccine candidate compatible with standard vaccine distribution channels, says J&J.
J&J has made supply agreements for its vaccine candidate with a number of countries: including the US (100 million doses); UK (30 million doses with option for an additional 22 million doses); and Canada (38 million doses)
US: Phase 3 trials for COVID-19 vaccine candidates
The J&J trial is being conducted in collaboration with Operation Warp Speed. It is the fourth Phase 3 COVIF-19 vaccine trial to launch in the US. Anthony S. Fauci, NIAID Director, said: “It is likely that multiple COVID-19 vaccine regimens will be required to meet the global need. The Janssen candidate has showed promise in early-stage testing and may be especially useful in controlling the pandemic if shown to be protective after a single dose.”
The other trials are Pfizer’s BNT162b2; Moderna’s mRNA-1273; and AstraZeneca’s AZD1222 trial.