Johnson & Johnson, the first single-dose shot to be authorised in Britain.The country's drug regulator gave the green light for the coronavirus vaccine, the Department of Health and Social Care said in a statement."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 four safe and effective vaccines approved to help protect people from this awful virus," UK Health Secretary Matt Hancock said.The government hopes the single-dose jab "will play an important role in the months to come", he added, as young people come forward for their vaccinations amid concern over the rise of the so-called variant first detected in India.Britain has ordered 20.