Dec 30 (Reuters) - Canada"s main stock index rose in thin trading for the sixth straight session on Thursday, helped by healthcare and mining shares, while easing fears over the impact of the Omicron coronavirus variant also boosted sentiment. At 9:44 a.m. ET (14:44 GMT), the Toronto Stock Exchange"s S&P/TSX composite index (.GSPTSE) was up 26.28 points, or 0.12%, at 21,370.93. Healthcare (.GSPTTHC) stocks rose 1.9%, rebounding from their worst day in over a month in the previous session, when cannabis stocks were under pressure due to tax-loss selling. Investors often exercise tax-loss selling strategies, dumping stocks that have performed poorly in order to reduce capital gains taxes, as the year draws to a close. Aiding sentiment were governments worldwide attempting to prevent economic damage by loosening isolation requirements rather than resorting to lockdowns, even as global COVID-19 cases surge to new highs. read more Studies have suggested Omicron is less deadly than some previous variants, but the number of people testing positive could overwhelm hospitals in some countries. "During Omicron fears, oil was sold off, but it"s recovered all those losses and other commodities are doing the same," said Gregory Taylor, portfolio manager at Purpose Investments, adding that the focus has now turned to future central bank actions. The financials sector (.SPTTFS) gained 0.2%, while the materials sector (.GSPTTMT), which includes precious and base metals miners and fertilizer companies, added 0.7%. HIGHLIGHTS The TSX posted nine new 52-week highs and one new low. Across all Canadian issues there were 37 new 52-week highs and 18 new lows, with a total volume of 25.59 million shares.