Prof Sir David Spiegelhalter, Cambridge University on precautionary suspension of AstraZeneca by several countries:

The precautionary principle favours inaction as a way of reducing risk. But the problem is that these are not normal times and inaction can be more risky than action.

Sometimes it can be harmful to wait for certainty. Not vaccinating people will costs lives.

'sometimes' is the key word - it admits that 'sometimes' it can be harmful to not wait - especially with vaccines. So it's not a winning argument by any stretch.

There's some interesting ethical stuff involved here - a lot of the discourse is that administering AstraZeneca outweighs the risks of not. That suggests it's better for a few thousand to potentially die of bloodclots than however many lives of elderly patients would be lost due to a pause on AstraZeneca. It is a difficult thing to weigh but given there are several alternative vaccines and AstraZeneca doesn't work against the Brazil or SA variant, i'd go for the pause - just to be sure.

Update: Germany, France, and Italy have resumed use of AZ following this report from European Medicines Agency (EMA)

Emer Cooke, EMA executive director: This is a safe and effective vaccine. Its benefits in protecting people from Covid-19 with the associated risks of death and hospitalisation outweigh the possible risks (although the EMA) could not rule out definitively a link between the vaccine and a small number of cases of rare and unusual but very serious clotting disorders.

Matt Hancock, British Health Secretary: Listen to the regulators. Get the jab.