Drugmaker Pfizer Inc said it could file for U.S. authorisation of the COVID-19 vaccine it is developing with German partner BioNTech as early as late November.
The blue-chip index closed up 1.5%, led by pharmaceutical, aero, bank and insurance stocks.
However, the FTSE 100 and the mid-cap index logged their first weekly declines in three weeks on concerns that the new tiered coronavirus restrictions across parts of England would derail a nascent economic recovery.
"With more than half of the country under 'high' restrictions, it's hard not to discount the possibility of even tighter restrictions over the winter months," wrote Deutsche Bank economist Sanjay Raja in a note.
"Despite the relatively modest increase in restrictions nationally, constraints on activity will almost certainly derail the UK's economic recovery."
Prime Minister Boris Johnson asked businesses to prepare for a no-trade deal Brexit unless the EU fundamentally changed course.
The mid-cap FTSE 250 index ended 0.1% lower as J D Wetherspoon Plc tumbled 19.4% after the pub operator posted an annual loss and announced job cuts as it called for "sensible" government measures to contain the health crisis.
Jupiter Fund Management Plc shed 3.3% after the asset manager suffered one billion pounds in net outflows in the third quarter.
Shares of oil major BP Plc rose 1.4% after falling to their lowest level since 1995 in the previous session.
Luxury goods maker Burberry Group Plc jumped 3.2% after the world's biggest luxury goods group, LVMH, said recovering sales of Louis Vuitton handbags had helped it contain the fallout from the pandemic in the third quarter.
(Reporting by Devik Jain in Bengaluru; editing by Uttaresh.V and Elaine Hardcastle)
By Devik Jain