U.S. stock index futures ticked higher on Thursday, helped by early data suggesting the Omicron variant of the coronavirus was less severe than feared, while investors looked ahead to weekly jobless claims and monthly inflation numbers Two vaccine makers said their shots offered protection against Omicron, as UK data suggested it may cause proportionally fewer hospitalizations than the Delta coronavirus variant, supporting conclusions reached in South Africa. World Health Organization officials have, however, warned against drawing firm conclusions about its virulence. As investors head into the new year following what has been a bumper year for the stock markets, the economic and health impact of Omicron variant will be in the spotlight. The S&P 500 is on track for an 87 percent gain since the end of 2018, its best three-year performance in more than two decades. “The new Omicron variant still casts its shadow over the economy, even though …