Johnson & Johnson on Thursday kicked off US human safety trials for its COVID-19 vaccine after releasing details of a study in monkeys that showed its best-performing vaccine candidate offered strong protection in a single dose.
When exposed to the virus, six out of six animals who got the vaccine candidate were completely protected from lung disease and five out of six were protected from infection as measured by the presence of virus in nasal swabs, according to the study published in the journal Nature.
“This gives us confidence that we can test a single-shot vaccine in this epidemic and learn whether it has a protective effect in humans,” Dr. Paul Stoffels, J&J’s chief scientific officer, told Reuters in a telephone interview.
The drugmaker said it had started early-stage human trials in the United States and Belgium and would test its vaccine candidate in over 1,000 healthy adults aged 18 to 55 years, as well as adults aged 65 years and older.
The US government is backing J&J’s vaccine effort with $456 million in funding as part of a spending spree aimed at speeding production of a vaccine to end the pandemic, which has infected millions and killed more than 660,000 people.
Stoffels said prior tests of this type of vaccine in other diseases found that a second shot significantly increases protection. But in a pandemic a single-shot vaccine has a significant advantage, sidestepping a lot of the logistical issues involved in getting people to come back for their second dose.
The company plans to take up the question of one or two doses in its phase 1 trial.
Depending on those results, J&J plans to start large-scale, phase 3 testing with a single-shot regimen in the second half of September. Around the same time, the company will start a parallel phase 3 study testing a two-shot regimen of the vaccine, Stoffels said.
J&J’s vaccine uses a common cold virus known as adenovirus type 26 or Ad26 to ferry coronavirus proteins into cells in the body, causing the body to mount an immune defense against the virus.