Johnson & Johnson (J&J)’s investigational single-dose Covid-19 vaccine, being developed by its subsidiary Janssen, has met all primary and key secondary endpoints in the Phase 3 ENSEMBLE clinical trial.

The Phase 3 ENSEMBLE trial is evaluating the efficacy and safety of the Janssen Covid-19 vaccine candidate in protecting moderate to severe Covid-19, with co-primary endpoints of 14 days and 28 days post-vaccination.

The top-line safety and efficacy data from the Phase 3 study are based on 43,783 participants.

Janssen’s Covid-19 vaccine candidate showed an overall effectiveness of 66% in preventing moderate to severe Covid-19, after 28 days from the date of vaccination. The onset of protection against the disease was observed by the 14th day.

The vaccine offered 72% protection against moderate to severe Covid-19 infection in the US, 66% in Latin America and 57% in South Africa, 28 days after the vaccination.

Johnson & Johnson chief executive officer and board of directors chairman Alex Gorsky said: “Johnson & Johnson embarked on the global effort to combat the COVID-19 pandemic a year ago, and has brought the full force of our capabilities, as well as tremendous public-private partnerships, to enable the development of a single-shot vaccine.

“Our goal all along has been to create a simple, effective solution for the largest number of people possible, and to have maximum impact to help end the pandemic.

“We’re proud to have reached this critical milestone and our commitment to address this global health crisis continues with urgency for everyone, everywhere.”

Janssen vaccine offered protection against severe Covid-19

The pharma company said that its vaccine candidate demonstrated 85% effectiveness in preventing severe disease across all regions, 28 days post-vaccination.

The vaccine has showed complete protection against Covid-related hospitalisation and death.

Also, the vaccine showed clear effect on Covid-19 cases needing medical intervention including hospitalisation, ICU admission, mechanical ventilation, extracorporeal membrane oxygenation (ECMO).

The analysis included a review of the available Phase 3 ENSEMBLE study safety data by the Data and Safety Monitoring Board (DSMB), an independent group of experts.

DSMB did not report any significant safety concerns relating to the vaccine, and a review of adverse events showed that a single-dose of Janssen’s Covid-19 vaccine candidate was generally well-tolerated.

Johnson & Johnson executive committee vice chairman and chief scientific officer Paul Stoffels said: “These topline results with a single-shot Covid-19 vaccine candidate represent a promising moment.

“The potential to significantly reduce the burden of severe disease, by providing an effective and well-tolerated vaccine with just one immunization, is a critical component of the global public health response.

“A one-shot vaccine is considered by the World Health Organization to be the best option in pandemic settings, enhancing access, distribution and compliance.

“Eighty-five percent efficacy in preventing severe Covid-19 disease and prevention of Covid-19-related medical interventions will potentially protect hundreds of millions of people from serious and fatal outcomes of Covid-19. It also offers the hope of helping ease the huge burden placed on healthcare systems and communities.”