The Oxford Covid jab is delivered this week. But when will vaccines bring results?

Fall or rise in coronavirus cases will not initially be a good measure of efficacy, say scientists devising ways to audit progress

Why is Britain delaying second doses of vaccine?

People in Britain are set to get their first shots of the Oxford/AstraZeneca vaccine on Monday, with millions of doses being given over the next few months. The mass vaccination of the UK’s population should bring an end to the country’s Covid-19 misery, but how long will it take for this immunisation programme to make a difference to our lives – and what will be the first signs that salvation is on the way?

These key issues will be anxiously pursued as the battle against Covid proceeds and daily cases involving the new virus variant continue to spread. However, scientists have warned that simply waiting for a reduction in new cases it not the way to tell whether the vaccine is starting to have an impact.