Traders wiped out all the gains made after this week's vaccine announcements from Moderna and Pfizer on Thursday as a third announcement, this time from AstraZeneca, failed to impress.

The FTSE 100 fell back to 6,334.35 by the end of the day, a 51-point drop, and lower than the 6,359 points the index had been at on Tuesday morning.

On Tuesday afternoon the announcement that Moderna's vaccine was effective nearly 95% of the time sent markets soaring, and they were boosted further on Wednesday as Pfizer upgraded its results.

But AstraZeneca's update did not reveal how effective the vaccine it is developing with the University of Oxford is, and the announcement failed to catch traders' imaginations.

So far the drugs giant's vaccine has been shown to provoke a good immune response, particularly among older people.

"Whilst this is great news, after the big hitting data from Pfizer and Moderna this week, AstraZeneca's was insufficient to overshadow fears of rising Covid cases, tighter lockdowns and the impact on the economy," said City Index analyst Fiona Cincotta.

"The IMF confirmed the market's fears warning that whilst the global economy is recovering from the depths of the Covid crisis, there are signs that the recovery is running out of steam, particularly in countries where cases are on the rise."

Other global markets also slipped. In the US, the S&P 500 had lost 0.2%, while the Dow Jones was down by twice that in the afternoon in London.

The Dax in Frankfurt lost 0.9%, while the Cac in Paris was down 0.7%.

Sterling was down by about 0.3% against both major rivals. One pound bought 1.3225 dollars or 1.1164 euros at the end of the day.

A report in the Financial Times on Thursday morning sunk shares in Cineworld, as the newspaper said that the struggling cinema chain might close some of its theatres, which have been empty for much of this year because of the Covid-19 pandemic. The company's value dropped by 8.7%.

Other news stories proved less dramatic. William Hill only budged slightly, up 0.5%, after shareholders approved plans to sell the company to Caesars for £2.9 billion.

Mulberry rose 1.9% after Mike Ashley's Frasers Group increased its stake in the luxury fashion brand. Mr Ashley's company fell by a slight 0.3%.

A good harvest for Naked Wines, as people shopped wine from their sofas, sent its revenue up 80% in the last six months, and its shares up by 0.9% on Thursday.

Airline Jet2 fared much worse. Travel restrictions have eaten into the bottom line at the carrier over the past half year, and shaved 4.2% off its share price.

At B&Q owner Kingfisher the story was different. Its sales have jumped over the past three months as locked down Britons looked at their homes and realised they could do with being fixed up. But the 17.6% rise in sales did not translate to the share price, which fell by 2.8%.

And finally, Royal Mail proved a winner on Thursday after presenting its results for the full year. As people turn to online shopping, postal workers have been delivering more and more parcels.

Royal Mail said that revenue from parcel delivery overtook those for letters for the first time as it increased its outlook. Shares closed up 6.5%.

The biggest risers on the FTSE 100 were Croda International, up 218p to 6,248p, Scottish Mortgage Investment Trust, up 34p to 1,044p, Halma, up 73p to 2,423p, WM Morrison, up 5.25p to 186.2p, and Relx, up 43.5p to 1,776.5p.

The biggest fallers on the FTSE 100 were Johnson Matthey, down 142p to 2,408p, Melrose Industries, down 7.75p to 158.15p, B&M, down 21.4p to 487.4p, Rolls-Royce, down 4.04p to 98.56p, and Hargreaves Lansdown, down 57.5p to 1,468.5p.