Americans are celebrating the arrival on home soil of batches of the world’s first single-shot coronavirus vaccine. The Johnson and Johnson jab, developed by the pharma giant’s Belgian subsidiary Janssen, gained US approval two days ago and its roll-out will begin tomorrow morning. The UK is not far behind. The government has already put in an order for 30 million J&J doses and the UK’s medical regulator, the MHRA, is expected to begin the formal approval process in the coming days.