1/23 We haven't had a lot to celebrate during this pandemic. But achieving the milestone of offering vaccine to the over 70s, health and care workers and the most clinically vulnerable just before target date is a huge cause for celebration, given the scale of the achievement.

2/23 When Margaret Keenan got her first jab in Coventry on December 8th last year, who’d have thought that, by Valentine’s Day, we’d have vaccinated over fourteen million people across the UK in just ten short weeks? Amazing, extraordinary and truly, really, world class!

3/23 I’ve been struck by how much joy and relief has been brought to those doing the vaccinations and those receiving them. A GP told me yesterday that nothing had given him greater pleasure in his long career. And that the patient's relief was sometimes overwhelming.

4/23 It's vital to recognise the extraordinary contribution of the staff and volunteers who have made this happen. One of my close family had their jab yesterday and was in awe of the volunteer standing outside in the freezing cold for a four hour shift meeting and greeting.

5/23 What I wanted to share in this thread was the slightly untold story of some of the extraordinary challenges the NHS has had to overcome to deliver this target. Requiring superhuman effort from NHS leaders and staff, way beyond the call of duty. Five challenges set out below.