The Janssen viral vector vaccine also demonstrated protection against multiple virus variants, including the South Africa B.1.351 lineage (15% of the study’s participants were based in South Africa). The company also champions the logistic advantages of a single-shot vaccine (most others currently authorized are two-dose vaccines) and thus its ability to protect more people more quickly.
The vaccine met primary endpoints in the interim analysis of its Phase 3 trial: with the single-shot found to be 66% effective against moderate to severe COVID-19 and 85% effective in preventing severe disease as of 28 days after vaccination.
Moderna’s COVID-19 vaccine reported 94.5% efficacy in Phase 3 trials while Pfizer’s reported 95%. These trials, however, defined prevention of any symptomatic COVID-19 cases – including mild cases - as the primary endpoint; whereas J&J’s 66% efficacy figure is based on the primary endpoint of prevention of moderate/severe COVID-19.
Protection from day 14
The Phase 3 ENSEMBLE study covered 43,783 participants aged 18+, accruing 468 symptomatic cases of COVID-19.
“Among all participants from different geographies and including those infected with an emerging viral variant, Janssen’s COVID-19 vaccine candidate was 66% effective overall in preventing moderate to severe COVID-19, 28 days after vaccination," reports the company. "The onset of protection was observed as early as day 14. The level of protection against moderate to severe COVID-19 infection was 72% in the US, 66% in Latin America and 57% in South Africa, 28 days post-vaccination.
“The Janssen COVID-19 vaccine candidate demonstrated complete protection against COVID-related hospitalization and death, 28 days post-vaccination. There was a clear effect of the vaccine on COVID-19 cases requiring medical intervention (hospitalization, ICU admission, mechanical ventilation, extracorporeal membrane oxygenation (ECMO)), with no reported cases among participants who had received the Janssen COVID-19 vaccine, 28 days post-vaccination.
"Protection was generally consistent across race, age groups, including adults over 60 years of age (N= 13,610), and across all variants and regions studied, including South Africa where nearly all cases of COVID-19 (95%) were due to infection with a SARS-CoV-2 variant from the B.1.351 lineage."
A review of Phase 3 safety data by the Data and Safety Monitoring Board (DSMB), an independent group of experts, did not report any significant safety concerns relating to the vaccine. A review of adverse events indicated that a single-dose of Janssen’s COVID-19 vaccine candidate was generally well-tolerated.
The Janssen vaccine candidate is compatible with standard vaccine distribution channels. The vaccine is estimated to remain stable for two years at -20°C (-4°F), at least three months of which can be at temperatures of 2-8°C (36°F–46°F). The company will ship the vaccine using the same cold chain technologies it uses today to transport other innovative medicines.
The company intends to file for EUA in the US in early February and expects to have product available to ship immediately following authorization. A rolling review is already under way in the EU.
J&J says its anticipated manufacturing timeline remains on schedule and the company is on track to meet its 2021 supply commitments, including those signed with governments and global organizations. Supply agreements for the vaccine include 100 million doses for the US and up to 400 million for the EU.
The vaccine
The Janssen COVID-19 vaccine candidate uses the company's AdVac viral vector vaccine platform, which was also used to develop and manufacture Janssen’s European Commission-approved Ebola vaccine regimen and construct its Zika, RSV, and HIV investigational vaccine candidates.
