Johnson &amp; Johnson on Thursday kicked off US human safety trials because of its COVID-19 vaccine after releasing details of a research in monkeys that showed its best-performing vaccine candidate offered strong defense in a single dose.

When subjected to this virus, six out of six animals who obtained the vaccine candidate proved completely protected from lung disease and five from six were protected from infection as measured by the existence of virus in nasal swabs, according to the study published in the journal Nature.

"This gives us confidence that we can examine a single-shot vaccine in this outbreak and find out whether it has a synergistic effect in humans," Dr. Paul Stoffels, J&amp;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 could test its own vaccine candidate at over 1,000 healthy adults aged 18 to 55 years, as well as adults aged 65 decades and older.

Even the US government is financing J&amp;J's vaccine campaign with $456 million in financing as part of a spending spree directed at speeding creation of a vaccine to end the outbreak, which has infected millions and killed over 660,000 people.

Stoffels said earlier evaluations of this kind of vaccine in different ailments found that a second shot appreciably increases protection. But in a pandemic that a single-shot vaccine has a significant advantage, sidestepping a lot of the logistical problems involved with getting people to come back to their second dose.

The company intends to take the question up of one or two doses at its stage 1 trial.

Depending on those results, J&amp;J plans to start large-scale, phase 3 testing using a single-shot regimen at the second half of September. Around precisely the identical period, the organization will begin a parallel stage 3 analysis testing a two-shot regimen of the vaccine, Stoffels stated.

J&amp;J's vaccine employs a standard cold virus called adenovirus type 26 or Ad26 to ferry coronavirus proteins into cells in the entire body, causing the body to mount an immune defense against the virus.

In the monkey study, scientists in J&amp;J and also Harvard's Beth Israel Deaconess Medical Center studied seven distinct possible vaccines in 32 creatures as compared with the results to 20 control creatures who got placebo shots.

Six months later, each one the animals were subjected to this SARS-CoV-2 virus. All of 20 creatures that received the placebo developed high levels of virus in their lungs and nasal swabs.

From the best-performing offender, which J&amp;J selected for human testing, not one of the animals had virus in their lungs and just one showed low levels of virus in nasal swabs. Laboratory tests demonstrated they all had grown antibodies capable of neutralizing the virus after one shot.

"This research indicates that even just a single immunization with the Ad26 vaccine leads to neutralizing antibody responses and robust protection of monkeys against COVID-19," explained Dr. Dan Barouch, a vaccine researcher at Beth Israel Deaconness who led the study in collaboration with J&amp;J.