An experimental vaccine candidate currently being developed by Johnson and Johnson has proved promising in early, pre-clinical studies.
The vaccine, Ad26.COV2.S, induced a robust immune response in monkeys, demonstrated by high levels of neutralising antibodies. According to J&J, this immune response successfully prevented subsequent infection and provided complete or near-complete protection from the SARS-CoV-2 virus, which causes COVID-19.
In the studies, J&J’s researchers initially immunised the animals with a number of vaccine candidates – out of seven vaccine prototypes tested in the study, scientists found that Ad26.COV2.S elicited the highest levels of neutralising antibodies to SARS-CoV-2.
All six animals that received a single immunisation with the lead vaccine candidate showed no detectable virus in their lower respiratory tract after exposure to SARS-CoV-2, and only one showed very low levels of the virus in a nasal swab at two time points.
Based on the promising results from the animal study, J&J has started a phase 1/2a human clinical trial of the vaccine trial in the US and Belgium. This clinical trial programme will evaluate both one- and two-dose regimens of Ad26.COV2.S in over 1,000 health adults aged 18 to 55 years, as well as adults aged 65 and over.
If all goes to plan in the first-in-human clinical trials, J&J hopes to begin a pivotal phase 3 trial of the single vaccine dose versus placebo in September, as well as a parallel phase 3 study of a two-dose regimen versus placebo.
The company added that it will emphasise representation of populations that have been the most impacted by the pandemic in the phase 3 trial programme. In the US, this would include significant representation of participants over 65 years of age and certain minority ethnic groups.
J&J and the US government’s Biomedical Advanced Research and Development Authority (BARDA) have collectively committed $1bn to the vaccine project, which will be spent on R&D and clinical testing of the vaccine.
“We are excited to see these pre-clinical data because they show our SARS-CoV-2 vaccine candidate generated a strong antibody response and provided protection with a single dose,” said Paul Stoffels, vice chairman of the executive committee and chief scientific officer, J&J.
“The findings give us confidence as we progress our vaccine development and upscale manufacturing in parallel, having initiated a phase 1/2a trial in July with the intention to move into a phase 3 trial in September,” he added.