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My latest @imperialcollege blog discusses the decision by the MHRA to license the AZ vaccine for use in the UK. The simpler storage requirements makes the vaccine highly suited for use by the NHS and offers a way to control the Covid-19 pandemic in the UK.
http://wwwf.imperial.ac.uk/blog/medical-centre/2020/12/30/the-nhs-must-be-fully-supported-in-rolling-out-the-covid-19-vaccination-programme/ …
The AZ1222 is cheaper and has easier storage requirements, though is 70% effective. Thus would it be preferable to use it for large scale vaccination programs, then relying on mRNA-1273 for high risk patients and patients the earlier vaccine did not work for?