LONDON: British stocks rose on optimism over a Covid-19 vaccine on Monday, although gains in the FTSE index were curbed by a fall in shares of AstraZeneca after the drugmaker's candidate was less effective than others in trials.

The mid cap index added 0.4%, while the FTSE 100 fell 0.3%, with AstraZeneca marking its worst day in nearly six months with a 3.8% fall. AstraZeneca said the average efficacy of its vaccine, which is being developed with the University of Oxford, was at 70% in its late-stage trial.

Although the British drugmaker said its potential vaccine can be 90% effective, its average rate was lower than for Pfizer-BioNTech's and Moderna's, which showed efficacy rates of about 94% to 95%. In corporate news, Cineworld Group jumped nearly 20% after it secured waivers for its debt covenants until June 2022, along with $450 million in new loans.

"Even though the late stage trials were better than expected, AstraZeneca's shares didn't get a booster shot," Susannah Streeter, senior investment and markets analyst, Hargreaves Lansdown, said of the news.

"It has though added to the overall positivity washing around the financial markets about a faster end to the pandemic."