The Johnson & Johnson single-dose Covid-19 vaccine has been approved in the UK, the Medicines and Healthcare products Regulatory Agency (MHRA) said on Friday.

This is the fourth Covid-19 vaccine to be authorised by the UK's independent regulator and is the first to be approved for protection against the Covid-19 with a single dose.

"We have undertaken a thorough review of the conditional marketing authorisation application submitted by Janssen (part of Johnson & Johnson), including the information on quality, safety and effectiveness. I am pleased to confirm today that this authorisation has been granted," MHRA Chief Executive June Raine said in a statement.

"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," Raine added.

The MHRA also obtained independent scientific advice from the Commission on Human Medicines (CHM) and its Covid-19 Expert Working Group.

The MHRA approval authorises the use of the vaccine in people aged 18 and over.

The decision on whether to use the vaccine in pregnant or breast-feeding women should be made in consultation with a healthcare professional after considering the benefits and risks, the statement reads.

The 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, similar to those seen in few people having the Oxford-AstraZeneca jab.