OTTAWA, April 12 (Reuters) - Business sentiment in Canada continues to improve and many firms consider the impacts of the COVID-19 pandemic behind them, though the outlook remains challenging for high-contact services, a Bank of Canada survey showed on Monday. The survey, conducted before new restrictions came into effect earlier this month to tackle a third wave, found sales were at or above pre-pandemic levels for 64% of businesses. “With uncertainty having receded and vaccination rollouts continuing, firms’ indicators of future sales have strengthened again,” the central bank said in its spring Business Outlook Survey. The BOS indicator hit its highest level since mid-2018. Still, nearly 20% of firms - many in high-contact services like tourism and non-essential retail - do not expect their sales to return to pre-pandemic levels in the next 12 months. The survey of 100 firms took place between February 16 to March 8, when COVID-19 cases were falling and second wave restrictions were being loosened.