The Johnson & Johnson single-dose coronavirus vaccine has been approved for use in the UK, the medicines regulator has said.
The vaccine, developed by the company’s pharmaceutical arm Janssen, has been shown to be 67% effective overall at preventing moderate to severe COVID-19, with some studies suggesting it also offers complete protection from admission to hospital and death.
In a statement, Health Secretary Matt Hancock described the approval as "a further boost to the UK’s hugely successful vaccination programme, which has already saved over 13,000 lives".
He added: "We now have four 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."
The UK has ordered 20 million doses of the vaccine, which England’s deputy chief medical officer, Professor Jonathan Van-Tam, has previously said could be used for hard-to-reach groups of people, where recalling them for a second jab is not always successful.
The Medicines and Healthcare products Regulatory Agency (MHRA) is thought to have held back from early approval of the vaccine after concerns were raised in the US about a link to extremely rare blood clots.
The clots are similar to those seen in a very small proportion of people having the Oxford-AstraZeneca jab.
In April, the use of the shot was suspended in the US while the US Centers for Disease Control and Prevention (CDC) investigated eight "serious" cases of rare blood clots associated with low blood platelets, among the seven million people who had been vaccinated.
One person died.
The vaccine’s rollout was resumed after a week – after concerns had been assuaged – but the European Medicines Agency recommended a warning about unusual blood clots with low blood platelet count should be added to the product information for the vaccine.
Johnson & Johnson has said the shot works across multiple variants of coronavirus.
Prime Minister Boris Johnson tweeted: "This is very welcome news and another boost to our hugely successful vaccination programme.
"As we encourage everyone to get their jabs, the single-dose Janssen vaccine will play an important role in helping us protect people from the virus.
"When you get the call, get the jab."
The vaccine is part of the UK’s Cov-Boost study which is looking at the effectiveness of a range of vaccines that could be used as a booster shot in the autumn.
The Joint Committee on Vaccination and Immunisation (JCVI) will now look at the jab’s data and provide guidance on who should receive it.
In a clinical trial involving 43,783 people, published earlier this year, the level of protection against moderate to severe COVID-19 infection was found to be 72% in the United States arm of the trial.
It was 66% in the Latin American arm of the trial, and 57% in the South African arm, where a mutant variant of the virus has been dominating.
The overall efficacy from these trials combined was 67%.