European shares hit a two-week high on Thursday as investor sentiment improved on signs the impact of the Omicron coronavirus variant may not be as severe as feared.

The pan-European STOXX 600 gained 0.4%, boosted by travel stocks, tracking a global share rally that was also helped by robust US economic data.

The risk of needing to stay in hospital for patients with Omicron may be 40% to 45% lower than for patients with the Delta variant, according to research by London's Imperial College.

Another study from South Africa found people diagnosed with Omicron in the country between Oct. 1 and Nov. 30 were 80% less likely to be admitted to hospital than those diagnosed with another variant in the same period.

"The Omicron wave won't derail the economic recovery that's well underway, it might delay it, but 2022 will have an attractive, healthy economic environment," said Philip Petursson, chief investment strategist at IG Wealth Management.

Amid concerns over slowing growth and restrictions due to the new COVID-19 variant, markets have been looking for clues about the global economic outlook into 2022. Several European bourses are closed, or will see a shortened trading session on Friday, while US markets are shut.

The STOXX 600 is set to gain for three straight sessions on slim trading volumes and could end the month almost 4% higher.

"This year, economies reopened from 2020 lockdowns and benefited from all the fiscal stimulus, 2022 will be the path to normalisation of equity returns, interest rates and economic growth," Petursson said.

AstraZeneca added to the positive sentiment after the drugmaker said a three-dose course of its COVID-19 vaccine was effective against the Omicron variant, citing data from an Oxford University lab study.

Swiss building materials company Holcim gained 2.4% after saying it would buy Malarkey Roofing Products for $1.35 billion to expand into the growing US residential roofing market.

Flutter Entertainment rose 3.4% after announcing it would buy Italian online gaming operator Sisal for 1.62 billion pounds ($2.16 billion), as the online betting group looks to expand its footprint in Europe.

Continental AG added 1.9% after its CEO told a magazine that the German automotive supplier could hit the upper end of its profit margin outlook in 2021 as vehicle production picked up in the fourth quarter.