![UK Prime Minister Boris Johnson looks down at the podium during a media briefing in Downing Street in January, 2021. Press Association](https://thenational-the-national-prod.cdn.arcpublishing.com/resizer/v2/MMJE7B5F3QMOETDZCJDRZEDVQQ.jpg?smart=true&auth=fc1100543fc1ae65260e38cd069e8d3b34a77b5aac8d6d1b68b013f0ecab3565&width=400&height=225)
UK Prime Minister Boris Johnson looks down at the podium during a media briefing in Downing Street in January, 2021. Press Association
UK Prime Minister Boris Johnson looks down at the podium during a media briefing in Downing Street in January, 2021. Press Association
What is the new Covid-19 Delta sub-strain spreading in the UK?
Scientists monitoring AY.4.2 believe it may be more transmissible than the strain first detected in India