Health Canada has granted full approval for Johnson & Johnson’s (J&J) single-dose Covid-19 vaccine for active immunisation to prevent infection in adults aged 18 years and older.

The vaccine is based on Janssen’s AdVac vaccine platform, which the company previously used to develop and produce its Ebola vaccine regime and construct its experimental Zika, respiratory syncytial virus and human immunodeficiency virus (HIV) vaccines.

Janssen’s Ebola vaccine secured approval from the European Commission last July.

The Health Canada approval was based on preliminary results from the randomised, placebo-controlled, double-blind Phase III ENSEMBLE clinical trial, which enrolled 43,783 adult subjects.

The trial assessed the single-dose vaccine’s safety and efficacy in offering protection against moderate to severe Covid-19.

It was carried out in eight nations across three continents and enrolled a diverse population, 35% of which was aged 60 years or older.

Results from the trial showed that the vaccine offered 85% effectiveness in preventing severe Covid-19.

It also provided protection against disease-associated hospitalisation and mortality 28 days after inoculation.

Janssen Research and Development global head Mathai Mammen said: “We are delighted by Health Canada’s decision to approve the J&J Covid-19 vaccine based on Phase III clinical data that proves the vaccine’s robust safety and efficacy.

“As vaccination rates continue to climb, a vaccine that prevents severe disease and protects against Covid-related hospitalisation and death will help ease the strain on healthcare systems and is an important option for people in Canada and around the world.”

Last month, the US Food and Drug Administration (FDA) granted emergency use authorisation for a ‘booster dose’ of the vaccine for adults aged 18 years and older.

In a real-world study in the US, the vaccine was found to provide stable vaccine efficiency of 79% for Covid-19 associated infections and 81% for hospitalisations linked to the disease.