The Janssen vaccine is the fourth COVID-19 jab to be approved in the UK and was reported earlier this year to be 66% effective in preventing COVID-19 and 85% effective in preventing severe COVID-19 in trials.
The government says it has ordered 20m doses of the vaccine for the UK and rollout is expected to begin later this year. The Joint Committee on Vaccination and Immunisation (JCVI) will issue advice on who should receive the vaccine before it becomes available.
MHRA chief executive Dr June Raine said: 'We have undertaken a thorough review of the conditional marketing authorisation application submitted by Janssen, including the information on quality, safety and effectiveness. I am pleased to confirm today that this authorisation has been granted.
'This is encouraging news for the public and the healthcare sector. We now have four safe and effective vaccines approved to help protect us from COVID-19.'
The Janssen vaccine, which uses an adenovirus vector to deliver the SARS-CoV-2 spike protein, similar to the AstraZeneca vaccine, is given as a single intramuscular injection. It can be stored at fridge temperatures of 2-8C for up to 3 months, making it ideal for distribution to care homes and other locations across the UK.
Health and Social Care Secretary Matt Hancock said: 'This is a further boost to the UK’s hugely successful vaccination programme, which has already saved over 13,000 lives, and means that we now have 4 safe and effective vaccines approved to help protect people from this awful virus.
'As Janssen is a single-dose vaccine, it will play an important role in the months to come as we redouble our efforts to encourage everyone to get their jabs and potentially begin a booster programme later this year.'
Similar to the AstraZeneca vaccine, thrombosis and thrombocytopenia - in some cases accompanied by bleeding - has been observed very rarely following administration of the Janssen vaccine.
Unlike the AstraZeneca vaccine, the Janssen jab is not contraindicated in patients with a history of heparin-induced thrombocytopenia and thrombosis (HITT or HIT type 2) but these individuals should only receive the vaccine if the potential benefits outweigh the potential risks.
Healthcare professionals should be alert to the signs and symptoms of thromboembolism and/or thrombocytopenia in all patients, the prescribing information for the vaccine says.