@Madcats
It's not often that I find myself in agreement with Tony Blair, but it seems a very sensible idea to give as many people as possible a single does of the current vaccine stock (so twice as many as planned) and live with the risk that they aren't as well protected.
I don't think GB has ever been in anything that an outside observer would call a "lockdown". They just keep closing pubs/restaurants and shops(ish).
It is not licensed for that dosage regime.
It's not clear whether it has been fully tested on that dosage regime, and if more evidence of efficacy at that dosage is needed, there would be a considerable delay.
The only scientists I have seen comment on this say they think it is a very bad idea. Speaking to a Commons Select Committee:
"Prof Peter Horby, who chairs the New and Emerging Respiratory Virus Threats Advisory Group (NERVTAG), said: "You can't assume that one dose is as good or half as good or whatever as good as two doses, because the data you have is on two doses."
Blair also said, entirely erroneously, that the aim of the vaccination is to prevent spread. As it is not known whether it does confer full sterilising immunity, the aim if to protect the vulnerable. The current two-dose regime prioritised by vulnerability will prevent over 90% of deaths and so very many hospitalisations. And also prevent NHS staff going off sick, so NHS has fewer worries about staff absences and has a chance of restoring more non-Covid services.
Once we protect the vulnerable (reducing their chances of serious disease to roughly that of a healthy young person) and NHS is buttressed, there is a chance we can start to relax restrictions and rebuild. If we instead choose to immunise healthy young people, then we will need restrictions for far longer, because the risk of overwhelming NHS from extensive serious disease in the more vulnerable population will continue at current level